43 CFR Part 3170 Subpart 3175

43 CFR Part 3170 Subpart 3175 (up to date as of 3/27/2023)
Measurement of Gas

43 CFR Part 3170 Subpart 3175

This content is from the eCFR and is authoritative but unofficial.

Title 43 - Public Lands: Interior
Subtitle B - Regulations Relating to Public Lands
Chapter II - Bureau of Land Management, Department of the Interior
Subchapter C - Minerals Management (3000)
Part 3170 - Onshore Oil and Gas Production
Authority: 25 U.S.C. 396d and 2107; 30 U.S.C. 189, 306, 359, and 1751; and 43 U.S.C. 1732(b), 1733, and 1740.
Source: 81 FR 81421, Nov. 17, 2016, unless otherwise noted.

Subpart 3175
§ 3175.10
§ 3175.20
§ 3175.30
§ 3175.31
§ 3175.40
§ 3175.41
§ 3175.42
§ 3175.43
§ 3175.44
§ 3175.45
§ 3175.46
§ 3175.47
§ 3175.48
§ 3175.49
§ 3175.60
§ 3175.61
§ 3175.70
§ 3175.80
§ 3175.90
§ 3175.91
§ 3175.92
§ 3175.93
§ 3175.94
§ 3175.100
§ 3175.101
§ 3175.102
§ 3175.103
§ 3175.104
§ 3175.110

Measurement of Gas
Definitions and acronyms.
General requirements.
Incorporation by reference.
Specific performance requirements.
Measurement equipment approved by standard or make and model.
Flange-tapped orifice plates.
Chart recorders.
Transducers.
Flow-computer software.
Gas chromatographs.
Isolating flow conditioners.
Differential primary devices other than flange-tapped orifice plates.
Linear measurement devices.
Accounting systems.
Timeframes for compliance.
Grandfathering.
Measurement location.
Flange-tapped orifice plates (primary devices).
Mechanical recorder (secondary device).
Installation and operation of mechanical recorders.
Verification and calibration of mechanical recorders.
Integration statements.
Volume determination.
Electronic gas measurement (secondary and tertiary device).
Installation and operation of electronic gas measurement systems.
Verification and calibration of electronic gas measurement systems.
Flow rate, volume, and average value calculation.
Logs and records.
Gas sampling and analysis.

43 CFR Part 3170 Subpart 3175 (enhanced display)

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43 CFR Part 3170 Subpart 3175 (up to date as of 3/27/2023)
Measurement of Gas

§ 3175.111
§ 3175.112
§ 3175.113
§ 3175.114
§ 3175.115
§ 3175.116
§ 3175.117
§ 3175.118
§ 3175.119
§ 3175.120
§ 3175.121
§ 3175.125
§ 3175.126
§ 3175.130
§ 3175.131
§ 3175.132
§ 3175.133
§ 3175.134
§ 3175.135
§ 3175.140
§ 3175.141
§ 3175.142
§ 3175.143
§ 3175.144
§ 3175.150

43 CFR Part 3170 Subpart 3175

General sampling requirements.
Sampling probe and tubing.
Spot samples - general requirements.
Spot samples - allowable methods.
Spot samples - frequency.
Composite sampling methods.
On-line gas chromatographs.
Gas chromatograph requirements.
Components to analyze.
Gas analysis report requirements.
Effective date of a spot or composite gas sample.
Calculation of heating value and volume
Reporting of heating value and volume.
Transducer testing protocol.
General requirements for transducer testing.
Testing of reference accuracy.
Testing of influence effects.
Transducer test reporting.
Uncertainty determination.
Flow-computer software testing.
General requirements for flow-computer software testing.
Required static tests.
Required dynamic tests.
Flow-computer software test reporting.
Immediate assessments.

Appendix A to Subpart 3175 of Part 3170
Table of Atmospheric Pressures
Subpart 3175 - Measurement of Gas
Source: 81 FR 81609, Nov. 17, 2016, unless otherwise noted.

§ 3175.10 Definitions and acronyms.
(a) As used in this subpart, the term:
AGA Report No. (followed by a number) means a standard prescribed by the American Gas Association,
with the number referring to the specific standard.

43 CFR 3175.10(a) “AGA Report No. (followed by a number)” (enhanced display)

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43 CFR Part 3170 Subpart 3175 (up to date as of 3/27/2023)
Measurement of Gas

43 CFR 3175.10(a) “Area ratio”

Area ratio means the smallest unrestricted area at the primary device divided by the cross-sectional area of
the meter tube. For example, the area ratio (Ar) of an orifice plate is the area of the orifice bore (Ad)
divided by the area of the meter tube (AD). For an orifice plate with a bore diameter (d) of 1.000
inches in a meter tube with an inside diameter (D) of 2.000 inches the area ratio is 0.25 and is
calculated as follows:

As-found means the reading of a mechanical or electronic transducer when compared to a certified test
device, prior to making any adjustments to the transducer.
As-left means the reading of a mechanical or electronic transducer when compared to a certified test
device, after making adjustments to the transducer, but prior to returning the transducer to service.
Atmospheric pressure means the pressure exerted by the weight of the atmosphere at a specific location.
Beta ratio means the measured diameter of the orifice bore divided by the measured inside diameter of the
meter tube. This is also referred to as a diameter ratio.
Bias means a systematic shift in the mean value of a set of measurements away from the true value of
what is being measured.
British thermal unit (Btu) means the amount of heat needed to raise the temperature of one pound of water
by 1 °F.
Component-type electronic gas measurement system means an electronic gas measurement system
comprising transducers and a flow computer, each identified by a separate make and model, from
which performance specifications are obtained.
Configuration log means a list of all fixed or user-programmable parameters used by the flow computer
that could affect the calculation or verification of flow rate, volume, or heating value.
Discharge coefficient means an empirically derived correction factor that is applied to the theoretical
differential flow equation in order to calculate a flow rate that is within stated uncertainty limits.
Effective date of a spot or composite gas sample means the first day on which the relative density and
heating value determined from the sample are used in calculating the volume and quality on which
royalty is based.
Electronic gas measurement (EGM) means all of the hardware and software necessary to convert the static
pressure, differential pressure, and flowing temperature developed as part of a primary device, to a
quantity, rate, or quality measurement that is used to determine Federal royalty. For orifice meters,
this includes the differential-pressure transducer, static-pressure transducer, flowing-temperature
transducer, on-line gas chromatograph (if used), flow computer, display, memory, and any internal or
external processes used to edit and present the data or values measured.

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43 CFR Part 3170 Subpart 3175 (up to date as of 3/27/2023)
Measurement of Gas

43 CFR 3175.10(a) “Element range”

Element range means the difference between the minimum and maximum value that the element
(differential-pressure bellows, static-pressure element, and temperature element) of a mechanical
recorder is designed to measure.
Event log means an electronic record of all exceptions and changes to the flow parameters contained
within the configuration log that occur and have an impact on a quantity transaction record.
GPA (followed by a number) means a standard prescribed by the Gas Processors Association, with the
number referring to the specific standard.
Heating value means the gross heat energy released by the complete combustion of one standard cubic
foot of gas at 14.73 pounds per square inch absolute (psia) and 60 °F.
Heating value variability means the deviation of previous heating values over a given time period from the
average heating value over that same time period, calculated at a 95 percent confidence level.
Unless otherwise approved by the BLM, variability is determined with the following equation:

Where:
V95% = heating value variability, %
σHV = standard deviation of the previous 5 heating values
2.776 = the “student-t” function for a probability of 0.05 and 4 degrees of freedom (degree of freedom is the
number of samples minus 1)
HV= the average heating value over the time period used to determine the standard deviation
High-volume facility measurement point or high-volume FMP means any FMP that measures more than 200
Mcf/day, but less than or equal to 1,000 Mcf/day over the averaging period.
Hydrocarbon dew point means the temperature at which hydrocarbon liquids begin to form within a gas
mixture. For the purpose of this regulation, the hydrocarbon dew point is the flowing temperature of
the gas measured at the FMP, unless otherwise approved by the AO.
Integration means a process by which the lines on a circular chart (differential pressure, static pressure,
and flowing temperature) used in conjunction with a mechanical chart recorder are re-traced or
interpreted in order to determine the volume that is represented by the area under the lines. An
integration statement documents the values determined from the integration.
Live input variable means a datum that is automatically obtained in real time by an EGM system.
Low-volume facility measurement point or low-volume FMP means any FMP that measures more than 35
Mcf/day, but less than or equal to 200 Mcf/day, over the averaging period.
Lower calibrated limit means the minimum engineering value for which a transducer was calibrated by
certified equipment, either in the factory or in the field.
Mean means the sum of all the values in a data set divided by the number of values in the data set.
43 CFR 3175.10(a) “Mean” (enhanced display)

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43 CFR Part 3170 Subpart 3175 (up to date as of 3/27/2023)
Measurement of Gas

43 CFR 3175.10(a) “Mole percent”

Mole percent means the number of molecules of a particular type that are present in a gas mixture divided
by the total number of molecules in the gas mixture, expressed as a percentage.
Normal flowing point means the differential pressure, static pressure, and flowing temperature at which an
FMP normally operates when gas is flowing through it.
Primary device means the volume-measurement equipment installed in a pipeline that creates a
measureable and predictable pressure drop in response to the flow rate of fluid through the pipeline.
It includes the pressure-drop device, device holder, pressure taps, required lengths of pipe upstream
and downstream of the pressure-drop device, and any flow conditioners that may be used to
establish a fully developed symmetrical flow profile.
Qualified test facility means a facility with currently certified measurement systems for mass, length, time,
temperature, and pressure traceable to the NIST primary standards or applicable international
standards approved by the BLM.
Quantity transaction record (QTR) means a report generated by an EGM system that summarizes the daily
and hourly volumes calculated by the flow computer and the average or totals of the dynamic data
that is used in the calculation of volume.
Reynolds number means the ratio of the inertial forces to the viscous forces of the fluid flow, and is defined
as:

Where:
Re = the Reynolds number
V = velocity
ρ = fluid density
D = inside meter tube diameter
µ = fluid viscosity
Redundancy verification means a process of verifying the accuracy of an EGM system by comparing the
readings of two sets of transducers placed on the same primary device.
Secondary device means the differential-pressure, static-pressure, and temperature transducers in an EGM
system, or a mechanical recorder, including the differential pressure, static pressure, and
temperature elements, and the clock, pens, pen linkages, and circular chart.
Self-contained EGM system means an EGM system in which the transducers and flow computer are
identified by a single make and model number from which the performance specifications for the
transducers and flow computer are obtained. Any change to the make or model numbers of either a
transducer or a flow computer within a self-contained EGM system changes the system to a
component-type EGM system.
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43 CFR Part 3170 Subpart 3175 (up to date as of 3/27/2023)
Measurement of Gas

43 CFR 3175.10(a) “Senior fitting”

Senior fitting means a type of orifice plate holder that allows the orifice plate to be removed, inspected, and
replaced without isolating and depressurizing the meter tube.
Standard cubic foot (scf) means a cubic foot of gas at 14.73 psia and 60 °F.
Standard deviation means a measure of the variation in a distribution, and is equal to the square root of the
arithmetic mean of the squares of the deviations of each value in the distribution from the arithmetic
mean of the distribution.
Tertiary device means, for EGM systems, the flow computer and associated memory, calculation, and
display functions.
Threshold of significance means the maximum difference between two data sets (a and b) that can be
attributed to uncertainty effects. The threshold of significance is determined as follows:

Where:
Ts = Threshold of significance, in percent
Ua = Uncertainty (95 percent confidence) of data set a, in percent
Ub = Uncertainty (95 percent confidence) of data set b, in percent
Transducer means an electronic device that converts a physical property such as pressure, temperature, or
electrical resistance into an electrical output signal that varies proportionally with the magnitude of
the physical property. Typical output signals are in the form of electrical potential (volts), current
(milliamps), or digital pressure or temperature readings. The term transducer includes devices
commonly referred to as transmitters.
Turndown means a reduction of the measurement range of a transducer in order to improve measurement
accuracy at the lower end of its scale. It is typically expressed as the ratio of the upper range limit to
the upper calibrated limit.
Type test means a test on a representative number of a specific make, model, and range of a device to
determine its performance over a range of operating conditions.
Uncertainty means the range of error that could occur between a measured value and the true value being
measured, calculated at a 95 percent confidence level.
Upper calibrated limit means the maximum engineering value for which a transducer was calibrated by
certified equipment, either in the factory or in the field.
Upper range limit (URL) means the maximum value that a transducer is designed to measure.
Verification means the process of determining the amount of error in a differential pressure, static
pressure, or temperature transducer or element by comparing the readings of the transducer or
element with the readings from a certified test device with known accuracy.
Very-low-volume facility measurement point or very-low-volume FMP means any FMP that measures 35
Mcf/day or less over the averaging period.
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43 CFR Part 3170 Subpart 3175 (up to date as of 3/27/2023)
Measurement of Gas

43 CFR 3175.10(a) “Very-high-volume facility measurement
point or very-high-volume FMP”

Very-high-volume facility measurement point or very-high-volume FMP means any FMP that measures more
than 1,000 Mcf/day over the averaging period.
(b) As used in this subpart the following additional acronyms carry the meaning prescribed:
GARVS means the BLM's Gas Analysis Reporting and Verification System.
GC means gas chromatograph.
GPA means the Gas Processors Association.
Mcf means 1,000 standard cubic feet.
psia means pounds per square inch - absolute.
psig means pounds per square inch - gauge.

§ 3175.20 General requirements.
Measurement of all gas at an FMP must comply with the standards prescribed in this subpart, except as otherwise
approved under § 3170.6 of this part.

§ 3175.30 Incorporation by reference.
(a) Certain material identified in this section is incorporated by reference into this part with the approval of
the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. Operators must comply with
all incorporated standards and material as they are listed in this section. To enforce any edition other than
that specified in this section, the BLM must publish a rule in the FEDERAL REGISTER and the material must
be reasonably available to the public. All approved material is available for inspection at the Bureau of
Land Management, Division of Fluid Minerals, 20 M Street SE., Washington, DC 20003, 202-912-7162; and
at all BLM offices with jurisdiction over oil and gas activities; and is available from the sources listed
below. It is also available for inspection at the National Archives and Records Administration (NARA). For
information on the availability of this material at NARA, call 202-741-6030 or go to
http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
(b) American Gas Association (AGA), 400 North Capitol Street NW., Suite 450, Washington, DC 20001;
telephone 202-824-7000.
(1) AGA Report No. 3, Orifice Metering of Natural Gas and Other Related Hydrocarbon Fluids, Second
Edition, September, 1985 (“AGA Report No. 3 (1985)”), IBR approved for §§ 3175.61(a) and (b),
3175.80(k), and 3175.94(a).
(2) AGA Transmission Measurement Committee Report No. 8, Compressibility Factors of Natural Gas
and Other Related Hydrocarbon Gases; Second Edition, November 1992 (“AGA Report No. 8”), IBR
approved for §§ 3175.103(a) and 3175.120(d).
(c) American Petroleum Institute (API), 1220 L Street NW., Washington, DC 20005; telephone 202-682-8000.
API also offers free, read-only access to some of the material at http://publications.api.org.
(1) API Manual of Petroleum Measurement Standards (MPMS) Chapter 14 - Natural Gas Fluids
Measurement, Section 1, Collecting and Handling of Natural Gas Samples for Custody Transfer;
Seventh Edition, May 2016 (“API 14.1”), IBR approved for §§ 3175.112(b) and (c), 3175.113(c), and
3175.114(b).

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43 CFR 3175.30(c)(2)

(2) API MPMS, Chapter 14, Section 3, Orifice Metering of Natural Gas and Other Related Hydrocarbon
Fluids - Concentric, Square-edged Orifice Meters, Part 1, General Equations and Uncertainty
Guidelines; Fourth Edition, September 2012; Errata, July 2013 (“API 14.3.1”), IBR approved for §
3175.31(a) and Table 1 to § 3175.80.
(3) API MPMS Chapter 14, Section 3, Orifice Metering of Natural Gas and Other Related Hydrocarbon
Fluids - Concentric, Square-edged Orifice Meters, Part 2, Specification and Installation Requirements;
Fifth Edition, March 2016 (“API 14.3.2”), IBR approved for §§ 3175.46(b) and (c), 3175.61(a),
3175.80(c) through (g) and (i) through (l), and Table 1 to § 3175.80.
(4) API MPMS Chapter 14, Section 3, Orifice Metering of Natural Gas and Other Related Hydrocarbon
Fluids - Concentric, Square-edged Orifice Meters, Part 3, Natural Gas Applications; Fourth Edition,
November 2013 (“API 14.3.3”), IBR approved for §§ 3175.94(a) and 3175.103(a).
(5) API MPMS Chapter 14, Natural Gas Fluids Measurement, Section 3, Concentric, Square-Edged Orifice
Meters, Part 3, Natural Gas Applications, Third Edition, August, 1992 (“API 14.3.3 (1992)”), IBR
approved for § 3175.61(b).
(6) API MPMS, Chapter 14, Section 5, Calculation of Gross Heating Value, Relative Density,
Compressibility and Theoretical Hydrocarbon Liquid Content for Natural Gas Mixtures for Custody
Transfer; Third Edition, January 2009; Reaffirmed February 2014 (“API 14.5”), IBR approved for §§
3175.120(c) and 3175.125(a).
(7) API MPMS Chapter 21, Section 1, Flow Measurement Using Electronic Metering Systems - Electronic
Gas Measurement; Second Edition, February 2013 (“API 21.1”), IBR approved for Table 1 to §
3175.100, §§ 3175.101(e), 3175.102(a) and (c) through (e), 3175.103(b) and (c), and 3175.104(a)
through (d).
(8) API MPMS Chapter 22 - Testing Protocol, Section 2, Differential Pressure Flow Measurement
Devices; First Edition, August 2005; Reaffirmed August 2012 (“API 22.2”), IBR approved for §
3175.47(b) through (d).
(d) Gas Processors Association (GPA), 6526 E. 60th Street, Tulsa, OK 74145; telephone 918-493-3872.
(1) GPA Standard 2166-05, Obtaining Natural Gas Samples for Analysis by Gas Chromatography Revised
2005 (“GPA 2166-05”), IBR approved for §§ 3175.113(c) and (d), 3175.114(a), and 3175.117(a).
(2) GPA Standard 2261-13, Analysis for Natural Gas and Similar Gaseous Mixtures by Gas
Chromatography; Revised 2013 (“GPA 2261-13”), IBR approved for § 3175.118(a) and (c).
(3) GPA Standard 2198-03, Selection, Preparation, Validation, Care and Storage of Natural Gas and
Natural Gas Liquids Reference Standard Blends; Revised 2003 (“GPA 2198-03”), IBR approved for §
3175.118(c).
(4) GPA Standard 2286-14, Method for the Extended Analysis of Natural Gas and Similar Gaseous
Mixtures by Temperature Program Gas Chromatography; Revised 2014 (“GPA 2286-14”), IBR
approved for § 3175.118(e).
(e) Pipeline Research Council International (PRCI), 3141 Fairview Park Dr., Suite 525, Falls Church, VA 22042;
telephone 703-205-1600.
(1) PRCI Contract-NX-19, Manual for the Determination of Supercompressibility Factors for Natural Gas;
December 1962 (“PRCI NX 19”), IBR approved for § 3175.61(b).
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43 CFR 3175.30(e)(2)

(2) [Reserved]

Note to paragraphs (b) through (e): You may also be able to purchase these standards from the
following resellers: Techstreet, 3916 Ranchero Drive, Ann Arbor, MI 48108; telephone
734-780-8000; www.techstreet.com/api/apigate.html; IHS Inc., 321 Inverness Drive South,
Englewood, CO 80112; 303-790-0600; www.ihs.com; SAI Global, 610 Winters Ave., Paramus, NJ
07652; telephone 201-986-1131; http://infostore.saiglobal.com/store/.

§ 3175.31 Specific performance requirements.
(a) Flow rate measurement uncertainty levels.
(1) For high-volume FMPs, the measuring equipment must achieve an overall flow rate measurement
uncertainty within ±3 percent.
(2) For very-high-volume FMPs, the measuring equipment must achieve an overall flow rate
measurement uncertainty within ±2 percent.
(3) The determination of uncertainty is based on the values of flowing parameters (e.g., differential
pressure, static pressure, and flowing temperature for differential meters or velocity, mass flow rate,
or volumetric flow rate for linear meters) determined as follows, listed in order of priority:
(i)

The average flowing parameters listed on the most recent daily QTR, if available to the BLM at
the time of uncertainty determination; or

(ii) The average flowing parameters from the previous day, as required under § 3175.101(b)(4)(i)
through (iii) (for differential meters).
(4) The uncertainty must be calculated under API 14.3.1, Section 12 (incorporated by reference, see §
3175.30) or other methods approved by the AO.
(b) Heating value uncertainty levels.
(1) For high-volume FMPs, the measuring equipment must achieve an annual average heating value
uncertainty within ±2 percent.
(2) For very-high-volume FMPs, the measuring equipment must achieve an annual average heating value
uncertainty within ±1 percent.
(3) Unless otherwise approved by the AO, the average annual heating value uncertainty must be
determined as follows:

(c) Bias. For low-volume, high-volume, and very-high-volume FMPs, the measuring equipment used for either
flow rate or heating value determination must achieve measurement without statistically significant bias.
(d) Verifiability. An operator may not use measurement equipment for which the accuracy and validity of any
input, factor, or equation used by the measuring equipment to determine quantity, rate, or heating value
are not independently verifiable by the BLM. Verifiability includes the ability to independently recalculate
the volume, rate, and heating value based on source records and field observations.
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43 CFR 3175.40

§ 3175.40 Measurement equipment approved by standard or make and model.
The measurement equipment described in §§ 3175.41 through 3175.49 is approved for use at FMPs under the
conditions and circumstances stated in those sections, provided it meets or exceeds the minimum standards
prescribed in this subpart.

§ 3175.41 Flange-tapped orifice plates.
Flange-tapped orifice plates that are constructed, installed, operated, and maintained in accordance with the
standards in § 3175.80 are approved for use.

§ 3175.42 Chart recorders.
Chart recorders used in conjunction with approved differential-type meters that are installed, operated, and
maintained in accordance with the standards in § 3175.90 are approved for use for low-volume and very-low-volume
FMPs only, and are not approved for high-volume or very-high-volume FMPs.

§ 3175.43 Transducers.
(a) A transducer of a specific make, model, and URL is approved for use in conjunction with differential
meters for high-volume or very-high-volume FMPs if it meets the following requirements:
(1) It has been type-tested under § 3175.130;
(2) The documentation required in § 3175.134 has been submitted to the PMT; and
(3) It has been approved by the BLM and placed on the list of type-tested equipment maintained at
www.blm.gov.
(b) A transducer of a specific make, model, and URL, in use at an FMP before January 17, 2017, is approved
for continued use if:
(1) Data supporting the published performance specification of the transducer are submitted to the PMT
in lieu of the documentation required in paragraph (a)(2) of this section; and
(2) It has been approved by the BLM and placed on the list of type-tested equipment maintained at
www.blm.gov.
(c) All transducers are approved for use at very-low- and low-volume FMPs.

§ 3175.44 Flow-computer software.
(a) A flow computer of a particular make and model, and equipped with a particular software version, is
approved for use at high- and very-high-volume FMPs if the flow computer and software version meet the
following requirements:
(1) The documentation required in § 3175.144 has been submitted to the PMT;
(2) The PMT has determined that the flow computer and software version passed the type-testing
required in § 3175.140, except as provided in paragraph (b) of this section; and
(3) The BLM has approved the flow computer and software version and has placed them on the list of
approved equipment maintained at www.blm.gov.
(b) Software versions (high- and very-high-volume FMPs).
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43 CFR 3175.44(b)(1)

(1) Software revisions that affect or have the potential to affect determination of flow rate,
determination of volume, determination of heating value, or data or calculations used to verify flow
rate, volume, or heating value must be type-tested under § 3175.140.
(2) Software revisions that do not affect or have the potential to affect the determination of flow rate,
determination of volume, determination of heating value, or data and calculations used to verify flow
rate, volume, or heating value are not required to be type-tested, however, the operator must provide
the BLM with a list of these software versions and a brief description of what changes were made
from the previous version. (The software manufacturer may provide such information instead of the
operator.)
(c) Software versions (low- and very-low-volume FMPs). All software versions are approved for use at lowand very-low-volume FMPs, unless otherwise required by the BLM.

§ 3175.45 Gas chromatographs.
GCs that meet the standards in §§ 3175.117 and 3175.118 for determining heating value and relative density are
approved for use.

§ 3175.46 Isolating flow conditioners.
The BLM will list on www.blm.gov the make, model, and size of isolating flow conditioner that is approved for use in
conjunction with a flange-tapped orifice plate, so long as the isolating flow conditioner is installed, operated, and
maintained in compliance with the requirements of this section. Approval of a particular make and model is
obtained as prescribed in this section.
(a) All testing required under this section must be performed at a qualified test facility not affiliated with the
flow-conditioner manufacturer.
(b) The operator or manufacturer must test the flow conditioner under API 14.3.2, Annex D (incorporated by
reference, see § 3175.30) and submit all test data to the BLM.
(c) The PMT will review the test data to ensure that the device meets the requirements of API 14.3.2, Annex D
(incorporated by reference, see § 3175.30) and make a recommendation to the BLM to either approve use
of the device, disapprove use of the device, or approve it with conditions for its use.
(d) If approved, the BLM will add the approved make and model, and any applicable conditions of use, to the
list maintained at www.blm.gov.

§ 3175.47 Differential primary devices other than flange-tapped orifice plates.
A make, model, and size of differential primary device listed at www.blm.gov is approved for use if it is installed,
operated, and maintained in compliance with any applicable conditions of use identified on www.blm.gov for that
device. Approval of a particular make and model is obtained as follows:
(a) All testing required under this section must be performed at a qualified test facility not affiliated with the
primary device manufacturer.
(b) The primary device must be tested under API 22.2 (incorporated by reference, see § 3175.30).
(c) The operator must submit to the BLM all test data required under API 22.2 (incorporated by reference, see
§ 3175.30). (The manufacturer of the primary device may submit such information instead of the
operator.)
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43 CFR 3175.47(d)

(d) The PMT will review the test data to ensure that the primary device meets the requirements of API 22.2
(incorporated by reference, see § 3175.30) and § 3175.31(c) and (d) and make a recommendation to the
BLM to either approve use of the device, disapprove use of the device, or approve its use with conditions.
(e) If the primary device is approved by the BLM, the BLM will add the approved make and model, and any
applicable conditions of use, to the list maintained at www.blm.gov.

§ 3175.48 Linear measurement devices.
A make, model, and size of linear measurement device listed at www.blm.gov is approved for use if it is installed,
operated, and maintained in compliance with any conditions of use identified on www.blm.gov for that device.
Approval of a particular make and model is obtained as follows:
(a) The linear measurement device must be tested at a qualified test facility not affiliated with the linearmeasurement-device manufacturer;
(b) The operator or manufacturer must submit to the BLM all test data required by the PMT;
(c) The PMT will review the test data to ensure that the linear measurement device meets the requirements of
§ 3175.31(c) and (d) and make a recommendation to the BLM to either approve use of the device,
disapprove use of the device, or approve its use with conditions; and
(d) If the linear measurement device is approved, the BLM will add the approved make and model, and any
applicable conditions of use, to the list maintained at www.blm.gov.

§ 3175.49 Accounting systems.
An accounting system with a name and version listed at www.blm.gov is approved for use in reporting logs and
records to the BLM. The approval is specific to those makes and models of flow computers for which testing
demonstrates compatibility. Approval for a particular name and version of accounting system used with a particular
make and model of flow computer is obtained as follows:
(a) For daily QTRs (see § 3175.104(a)), an operator or vendor must submit daily QTRs to the BLM both from
the accounting system and directly from the flow computer for at least 6 consecutive monthly reporting
periods;
(b) For hourly QTRs (see § 3175.104(a)), an operator must submit hourly QTRs to the BLM both from the
accounting system and directly from the flow computer for at least 15 consecutive daily reporting
periods. (A vendor may submit such information on behalf of an operator);
(c) For configuration logs (see § 3175.104(b)), an operator must submit at least 10 configuration logs to the
BLM taken at random times covering a span of at least 6 months both from the accounting system and
directly from the flow computer. (A vendor may submit such information on behalf of an operator);
(d) For event logs (see § 3175.104(c)), an operator must submit an event log to the BLM containing at least
50 events both from the accounting system and directly from the flow computer. (A vendor may submit
such information on behalf of an operator);
(e) For alarm logs (see § 3175.104(d)), an operator must submit an alarm log to the BLM containing at least
50 alarm conditions both from the accounting system and directly from the flow computer (a vendor may
submit such information on behalf of an operator);

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(f) The BLM may require additional tests and records that may be necessary to determine that the software
meets the requirements of § 3175.104(a);
(g) The records retrieved directly from the flow computer in paragraphs (a) through (d) of this section must be
unedited;
(h) The records retrieved from the accounting system in paragraphs (a) through (d) must include both edited
and unedited versions; and
(i)

The BLM will approve the accounting system name and version for use with the make and model of flow
computer used for comparison, and add the system name and version to the list of approved systems
maintained at www.blm.gov if:
(1) The BLM compares the records retrieved directly from the flow computer with the unedited records
from the accounting system and there are no significant discrepancies; and
(2) The BLM compares the records retrieved directly from the flow computer with the edited records
from the accounting system and all changes are clearly indicated, the reason for each change is
indicated or is available upon request, and the edited version is clearly distinguishable from the
unedited version.

§ 3175.60 Timeframes for compliance.
(a) New FMPs.
(1) Except as allowed in paragraphs (a)(2) through (4) of this section, the measuring procedures and
equipment installed at any FMP on or after January 17, 2017 must comply with all of the
requirements of this subpart upon installation.
(2) The gas analysis reporting requirements of § 3175.120(e) and (f) will begin on January 17, 2019.
(3) High- and very-high-volume FMPs must comply with the sampling frequency requirements of §
3175.115(b) starting on January 17, 2019. Between January 17, 2017 and January 17, 2019, the
initial sampling frequencies required at high- and very-high-volume FMPs are those listed in Table 1
to § 3175.110.
(4) Equipment approvals required in §§ 3175.43, 3175.44, and 3175.46 through 3175.49 will be required
after January 17, 2019.
(b) Existing FMPs.
(1) Except as allowed in § 3175.61, measuring procedures and equipment at any FMP in place before
January 17, 2017 must comply with the requirements of this subpart within the timeframes specified
in this paragraph (b).
(2) High- and very-high-volume FMPs must comply with:
(i)

All of the requirements of this subpart except as specified in paragraphs (b)(2)(ii) and (iii) of
this section by January 17, 2018;

(ii) The gas analysis reporting requirements of § 3175.120(e) and (f) starting on January 17, 2019;
and
(iii) Equipment approvals required in §§ 3175.43, 3175.44, and 3175.46 through 3175.49 starting on
January 17, 2019.
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(3) Low-volume FMPs must comply with all of the requirements of this subpart by January 17, 2019.
(4) Very-low-volume FMPs must comply with all of the requirements of this subpart by January 17, 2020.
(c) During the phase-in timeframes in paragraph (b) of this section, measuring procedures and equipment in
place before January 17, 2017 must comply with the requirements in place prior to the issuance of this
rule, including Onshore Oil and Gas Order No. 5, Measurement of Gas, and applicable NTLs, COAs, and
written orders.
(d) Onshore Oil and Gas Order No. 5, Measurement of Gas, statewide NTLs, variance approvals, and written
orders that establish requirements or standards related to gas measurement and that are in effect on
January 17, 2017 are rescinded as of:
(1) January 17, 2018 for high-volume and very-high-volume FMPs;
(2) January 17, 2019 for low-volume FMPs; and
(3) January 17, 2020 for very-low-volume FMPs.

§ 3175.61 Grandfathering.
(a) Meter tubes. Meter tubes installed at high- and low-volume FMPs before January 17, 2017 are exempt
from the meter tube requirements of API 14.3.2, Subsection 6.2 (incorporated by reference, see §
3175.30), and § 3175.80(f) and (k). For high-volume FMPs, the BLM will add an uncertainty of ±0.25
percent to the discharge coefficient uncertainty when determining overall meter uncertainty under §
3175.31(a), unless the PMT reviews, and the BLM approves, data showing otherwise. Meter tubes
grandfathered under this section must still meet the following requirements:
(1) Orifice plate eccentricity must comply with AGA Report No. 3 (1985), Section 4.2.4 (incorporated by
reference, see § 3175.30).
(2) Meter tube construction and condition must comply with AGA Report No. 3 (1985), Section 4.3.4
(incorporated by reference, see § 3175.30).
(3) Meter tube lengths.
(i)

Meter tube lengths must comply with AGA Report No. 3 (1985), Section 4.4 (dimensions “A” and
“A'” from Figures 4-8) (incorporated by reference, see § 3175.30).

(ii) If the upstream meter tube contains a 19-tube bundle flow straightener or isolating flow
conditioner, the installation must comply with § 3175.80(g);
(b) EGM software.
(1) EGM software installed at very-low-volume FMPs before January 17, 2017 is exempt from the
requirements in § 3175.103(a)(1). However, flow-rate calculations must still be calculated in
accordance with AGA Report No. 3 (1985), Section 6, or API 14.3.3 (1992), and supercompressibility
calculations must still be calculated in accordance with PRCI NX 19 (all incorporated by reference,
see § 3175.30).
(2) EGM software installed at low-volume FMPs before January 17, 2017 is exempt from the
requirements at § 3175.103(a)(1)(i) if the differential-pressure to static-pressure ratio, based on the
monthly average differential pressure and static pressure, is less than the value of “xi” shown in API

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43 CFR 3175.70

14.3.3 (1992), Annex G, Table G.1 (incorporated by reference, see § 3175.30). However, flow-rate
calculations must still be calculated in accordance with API 14.3.3 (1992) (incorporated by
reference, see § 3175.30).

§ 3175.70 Measurement location.
(a) Commingling and allocation. Gas produced from a lease, unit PA, or CA may not be commingled with
production from other leases, unit PAs, CAs, or non-Federal properties before the point of royalty
measurement, unless prior approval is obtained under 43 CFR subpart 3173.
(b) Off-lease measurement. Gas must be measured on the lease, unit, or CA unless approval for off-lease
measurement is obtained under 43 CFR subpart 3173.

§ 3175.80 Flange-tapped orifice plates (primary devices).
Except as stated in this section, as prescribed in Table 1 to this section, or grandfathered under § 3175.61, the
standards and requirements in this section apply to all flange-tapped orifice plates (Note: The following table lists
the standards in this subpart and the API standards that the operator must follow to install and maintain flangetapped orifice plates. A requirement applies when a column is marked with an “x” or a number.).

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43 CFR 3175.80(a)

(a) The Beta ratio must be no less than 0.10 and no greater than 0.75.
(b) The orifice bore diameter must be no less than 0.45 inches.

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43 CFR 3175.80(c)

(c) For FMPs measuring production from wells first coming into production, or from existing wells that have
been re-fractured (including FMPs already measuring production from one or more other wells), the
operator must inspect the orifice plate upon installation and then every 2 weeks thereafter. If the
inspection shows that the orifice plate does not comply with API 14.3.2, Section 4 (incorporated by
reference, see § 3175.30), the operator must replace the orifice plate. When the inspection shows that the
orifice plate complies with API 14.3.2, Section 4 (incorporated by reference, see § 3175.30), the operator
thereafter must inspect the orifice plate as prescribed in paragraph (d) of this section.
(d) The operator must pull and inspect the orifice plate at the frequency (in months) identified in Table 1 to
this section. The operator must replace orifice plates that do not comply with API 14.3.2, Section 4
(incorporated by reference, see § 3175.30), with an orifice plate that does comply with these standards.
(e) The operator must retain documentation for every plate inspection and must include that documentation
as part of the verification report (see § 3175.92(d) for mechanical recorders, or § 3175.102(e) for EGM
systems). The operator must provide that documentation to the BLM upon request. The documentation
must include:
(1) The information required in § 3170.7(g) of this part;
(2) Plate orientation (bevel upstream or downstream);
(3) Measured orifice bore diameter;
(4) Plate condition (compliance with API 14.3.2, Section 4 (incorporated by reference, see § 3175.30));
(5) The presence of oil, grease, paraffin, scale, or other contaminants on the plate;
(6) Time and date of inspection; and
(7) Whether or not the plate was replaced.
(f) Meter tubes must meet the requirements of API 14.3.2, Subsections 5.1 through 5.4 (incorporated by
reference, see § 3175.30).
(g) If flow conditioners are used, they must be either isolating-flow conditioners approved by the BLM and
installed under BLM requirements (see § 3175.46) or 19-tube-bundle flow straighteners constructed in
compliance with API 14.3.2, Subsections 5.5.2 through 5.5.4, and located in compliance with API 14.3.2,
Subsection 6.3 (incorporated by reference, see § 3175.30).
(h) Basic meter tube inspection. The operator must:
(1) Perform a basic inspection of meter tubes within the timeframe (in years) specified in Table 1 to this
section;
(2) Conduct a basic inspection that is able to identify obstructions, pitting, and buildup of foreign
substances (e.g., grease and scale);
(3) Notify the AO at least 72 hours in advance of performing a basic inspection or submit a monthly or
quarterly schedule of basic inspections to the AO in advance;
(4) Conduct additional inspections, as the AO may require, if warranted by conditions, such as corrosive
or erosive-flow (e.g., high H2S or CO2 content) or signs of physical damage to the meter tube;
(5) Maintain documentation of the findings from the basic meter tube inspection including:
(i)

The information required in § 3170.7(g) of this part;

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43 CFR 3175.80(h)(5)(ii)

(ii) The time and date of inspection;
(iii) The type of equipment used to make the inspection; and
(iv) A description of findings, including location and severity of pitting, obstructions, and buildup of
foreign substances; and
(6) Complete the first inspection after January 17, 2017 within the timeframes (in years) given in Table 1
to this section.
(i)

Detailed meter tube inspection.
(1) Within 30 days of a basic inspection that indicates the presence of pitting, obstructions, or a buildup
of foreign substances, the operator must:
(i)

For low-volume FMPs, clean the meter tube of obstructions and foreign substances;

(ii) For high- and very-high-volume FMPs, physically measure and inspect the meter tube to
determine if the meter tube complies with API 14.3.2, Subsections 5.1 through 5.4 and API
14.3.2, Subsection 6.2 (incorporated by reference, see § 3175.30), or the requirements under §
3175.61(a), if the meter tube is grandfathered under § 3175.61(a). If the meter tube does not
comply with the applicable standards, the operator must repair the meter tube to bring the
meter tube into compliance with these standards or replace the meter tube with one that meets
these standards; or
(iii) Submit a request to the AO for an extension of the 30-day timeframe, justifying the need for the
extension.
(2) For all high- and very-high volume FMPs installed after January 17, 2017, the operator must perform
a detailed inspection under paragraph (i)(1)(ii) of this section before operation of the meter. The
operator may submit documentation showing that the meter tube complies with API 14.3.2,
Subsections 5.1 through 5.4 (incorporated by reference, see § 3175.30) in lieu of performing a
detailed inspection.
(3) The operator must notify the AO at least 24 hours before performing a detailed inspection.
(j)

The operator must retain documentation of all detailed meter tube inspections, demonstrating that the
meter tube complies with API 14.3.2, Subsections 5.1 through 5.4 (incorporated by reference, see §
3175.30), and showing all required measurements. The operator must provide such documentation to the
BLM upon request for every meter-tube inspection. Documentation must also include the information
required in § 3170.7(g) of this part.

(k) Meter tube lengths.
(1) Meter-tube lengths and the location of 19-tube-bundle flow straighteners, if applicable, must comply
with API 14.3.2, Subsection 6.3 (incorporated by reference, see § 3175.30).
(2) For Beta ratios of less than 0.5, the location of 19-tube bundle flow straighteners installed in
compliance with AGA Report No. 3 (1985), Section 4.4 (incorporated by reference, see § 3175.30),
also complies with the location of 19-tube bundle flow straighteners as required in paragraph (k)(1)
of this section.

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43 CFR 3175.80(k)(3)

(3) If the diameter ratio (β) falls between the values in Tables 7, 8a, or 8b of API 14.3.2, Subsection 6.3
(incorporated by reference, see § 3175.30), the length identified for the larger diameter ratio in the
appropriate Table is the minimum requirement for meter-tube length and determines the location of
the end of the 19-tube-bundle flow straightener closest to the orifice plate. For example, if the
calculated diameter ratio is 0.41, use the table entry for a 0.50 diameter ratio.
(l)

Thermometer wells.
(1) Thermometer wells used for determining the flowing temperature of the gas as well as thermometer
wells used for verification (test well) must be located in compliance with API 14.3.2, Subsection 6.5
(incorporated by reference, see § 3175.30).
(2) Thermometer wells must be located in such a way that they can sense the same flowing gas
temperature that exists at the orifice plate. The operator may accomplish this by physically locating
the thermometer well(s) in the same ambient temperature conditions as the primary device (such as
in a heated meter house) or by installing insulation and/or heat tracing along the entire meter run. If
the operator chooses to use insulation to comply with this requirement, the AO may prescribe the
quality of the insulation based on site specific factors such as ambient temperature, flowing
temperature of the gas, composition of the gas, and location of the thermometer well in relation to
the orifice plate (i.e., inside or outside of a meter house).
(3) Where multiple thermometer wells have been installed in a meter tube, the flowing temperature must
be measured from the thermometer well closest to the primary device.
(4) Thermometer wells used to measure or verify flowing temperature must contain a thermally
conductive liquid.

(m) The sampling probe must be located as specified in § 3175.112(b).

§ 3175.90 Mechanical recorder (secondary device).
(a) The operator may use a mechanical recorder as a secondary device only on very-low-volume and lowvolume FMPs.
(b) Table 1 to this section lists the standards that the operator must follow to install, operate, and maintain
mechanical recorders. A requirement applies when a column is marked with an “x” or a number.

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43 CFR 3175.91

§ 3175.91 Installation and operation of mechanical recorders.
(a) Gauge lines connecting the pressure taps to the mechanical recorder must:
(1) Have a nominal diameter of not less than 3/8 inch, including ports and valves;

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(2) Be sloped upwards from the pressure taps at a minimum pitch of 1 inch per foot of length with no
visible sag;
(3) Be the same internal diameter along their entire length;
(4) Not include tees, except for the static-pressure line;
(5) Not be connected to more than one differential-pressure bellows and static-pressure element, or to
any other device; and
(6) Be no longer than 6 feet.
(b) The differential-pressure pen must record at a minimum reading of 10 percent of the differential-pressurebellows range for the majority of the flowing period. This requirement does not apply to inverted charts.
(c) The flowing temperature of the gas must be continuously recorded and used in the volume calculations
under § 3175.94(a)(1).
(d) The following information must be maintained at the FMP in a legible condition, in compliance with §
3170.7(g) of this part, and accessible to the AO at all times:
(1) Differential-pressure-bellows range;
(2) Static-pressure-element range;
(3) Temperature-element range;
(4) Relative density (specific gravity) of the gas;
(5) Static-pressure units of measure (psia or psig);
(6) Meter elevation;
(7) Meter-tube inside diameter;
(8) Primary device type;
(9) Orifice-bore or other primary-device dimensions necessary for device verification, Beta- or area-ratio
determination, and gas-volume calculation;
(10) Make, model, and location of approved isolating flow conditioners, if used;
(11) Location of the downstream end of 19-tube-bundle flow straighteners, if used;
(12) Date of last primary-device inspection; and
(13) Date of last meter verification.
(e) The differential pressure, static pressure, and flowing temperature elements must be operated between
the lower- and upper-calibrated limits of the respective elements.

§ 3175.92 Verification and calibration of mechanical recorders.
(a) Verification after installation or following repair.
(1) Before performing any verification of a mechanical recorder required in this part, the operator must
perform a leak test. The verification must not proceed if leaks are present. The leak test must be
conducted in a manner that will detect leaks in the following:

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(i)

43 CFR 3175.92(a)(1)(i)

All connections and fittings of the secondary device, including meter manifolds and verification
equipment;

(ii) The isolation valves; and
(iii) The equalizer valves.
(2) The operator must adjust the time lag between the differential- and static-pressure pens, if
necessary, to be 1/96 of the chart rotation period, measured at the chart hub. For example, the time
lag is 15 minutes on a 24-hour test chart and 2 hours on an 8-day test chart.
(3) The meter's differential pen arc must be able to duplicate the test chart's time arc over the full range
of the test chart, and must be adjusted, if necessary.
(4) The as-left values must be verified in the following sequence against a certified pressure device for
the differential-pressure and static-pressure elements (if the static-pressure pen has been offset for
atmospheric pressure, the static-pressure element range is in psia):
(i)

Zero (vented to atmosphere);

(ii) 50 percent of element range;
(iii) 100 percent of element range;
(iv) 80 percent of element range;
(v) 20 percent of element range; and
(vi) Zero (vented to atmosphere).
(5) The following as-left temperatures must be verified by placing the temperature probe in a water bath
with a certified test thermometer:
(i)

Approximately 10 °F below the lowest expected flowing temperature;

(ii) Approximately 10 °F above the highest expected flowing temperature; and
(iii) At the expected average flowing temperature.
(6) If any of the readings required in paragraph (a)(4) or (5) of this section vary from the test device
reading by more than the tolerances shown in Table 1 to this section, the operator must replace and
verify the element for which readings were outside the applicable tolerances before returning the
meter to service.

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(7) If the static-pressure pen is offset for atmospheric pressure:
(i)

The atmospheric pressure must be calculated under appendix A to this subpart; and

(ii) The pen must be offset prior to obtaining the as-left verification values required in paragraph
(a)(4) of this section.
(b) Routine verification frequency. The differential pressure, static pressure, and temperature elements must
be verified under the requirements of this section at the frequency specified in Table 1 to § 3175.90, in
months.
(c) Routine verification procedures.
(1) Before performing any verification required in this part, the operator must perform a leak test in the
manner required under paragraph (a)(1) of this section.
(2) No adjustments to the pens or linkages may be made until an as-found verification is obtained. If the
static pen has been offset for atmospheric pressure, the static pen must not be reset to zero until
the as-found verification is obtained.
(3) The operator must obtain the as-found values of differential and static pressure against a certified
pressure device at the readings listed in paragraph (a)(4) of this section, with the following additional
requirements:
(i)

If there is sufficient data on site to determine the point at which the differential and static pens
normally operate, the operator must also obtain an as-found value at those points;

(ii) If there is not sufficient data on site to determine the points at which the differential and static
pens normally operate, the operator must also obtain as-found values at 5 percent of the
element range and 10 percent of the element range; and

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(iii) If the static-pressure pen has been offset for atmospheric pressure, the static-pressure element
range is in units of psia.
(4) The as-found value for temperature must be taken using a certified test thermometer placed in a test
thermometer well if there is flow through the meter and the meter tube is equipped with a test
thermometer well. If there is no flow through the meter or if the meter is not equipped with a test
thermometer well, the temperature probe must be verified by placing it along with a test
thermometer in an insulated water bath.
(5) The element undergoing verification must be calibrated according to manufacturer specifications if
any of the as-found values determined under paragraph (c)(3) or (4) of this section are not within the
tolerances shown in Table 1 to this section, when compared to the values applied by the test
equipment.
(6) The operator must adjust the time lag between the differential- and static-pressure pens, if
necessary, to be 1/96 of the chart rotation period, measured at the chart hub. For example, the time
lag is 15 minutes on a 24-hour test chart and 2 hours on an 8-day test chart.
(7) The meter's differential pen arc must be able to duplicate the test chart's time arc over the full range
of the test chart, and must be adjusted, if necessary.
(8) If any adjustment to the meter was made, the operator must perform an as-left verification on each
element adjusted using the procedures in paragraphs (c)(3) and (4) of this section.
(9) If, after an as-left verification, any of the readings required in paragraph (c)(3) or (4) of this section
vary by more than the tolerances shown in Table 1 to this section when compared with the testdevice reading, any element which has readings that are outside of the applicable tolerances must
be replaced and verified under this section before the operator returns the meter to service.
(10) If the static-pressure pen is offset for atmospheric pressure:
(i)

The atmospheric pressure must be calculated under appendix A to this subpart; and

(ii) The pen must be offset prior to obtaining the as-left verification values required in paragraph
(c)(3) of this section.
(d) The operator must retain documentation of each verification, as required under § 3170.7(g) of this part,
and submit it to the BLM upon request. This documentation must include:
(1) The time and date of the verification and the prior verification date;
(2) Primary-device data (meter-tube inside diameter and differential-device size and Beta or area ratio) if
the orifice plate is pulled and inspected;
(3) The type and location of taps (flange or pipe, upstream or downstream static tap);
(4) Atmospheric pressure used to offset the static-pressure pen, if applicable;
(5) Mechanical recorder data (make, model, and differential pressure, static pressure, and temperature
element ranges);
(6) The normal operating points for differential pressure, static pressure, and flowing temperature;
(7) Verification points (as-found and applied) for each element;
(8) Verification points (as-left and applied) for each element, if a calibration was performed;
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(9) Names, contact information, and affiliations of the person performing the verification and any
witness, if applicable; and
(10) Remarks, if any.
(e) Notification of verification.
(1) For verifications performed after installation or following repair, the operator must notify the AO at
least 72 hours before conducting the verifications.
(2) For routine verifications, the operator must notify the AO at least 72 hours before conducting the
verification or submit a monthly or quarterly verification schedule to the AO in advance.
(f) If, during the verification, the combined errors in as-found differential pressure, static pressure, and
flowing temperature taken at the normal operating points tested result in a flow-rate error greater than 2
percent or 2 Mcf/day, whichever is greater, the volumes reported on the OGOR and on royalty reports
submitted to ONRR must be corrected beginning with the date that the inaccuracy occurred. If that date is
unknown, the volumes must be corrected beginning with the production month that includes the date that
is half way between the date of the last verification and the date of the current verification. For example:
Meter verification determined that the meter was reading 4 Mcf/day high at the normal operating points.
The average flow rate measured by the meter is 90 Mcf/day. There is no indication of when the inaccuracy
occurred. The date of the current verification was December 15, 2015. The previous verification was
conducted on June 15, 2015. The royalty volumes reported on OGOR B that were based on this meter
must be corrected for the 4 Mcf/day error back to September 15, 2015.
(g) Test equipment used to verify or calibrate elements at an FMP must be certified at least every 2 years.
Documentation of the recertification must be on-site during all verifications and must show:
(1) Test equipment serial number, make, and model;
(2) The date on which the recertification took place;
(3) The test equipment measurement range; and
(4) The uncertainty determined or verified as part of the recertification.

§ 3175.93 Integration statements.
An unedited integration statement must be retained and made available to the BLM upon request. The integration
statement must contain the following information:
(a) The information required in § 3170.7(g) of this part;
(b) The name of the company performing the integration;
(c) The month and year for which the integration statement applies;
(d) Meter-tube inside diameter (inches);
(e) The following primary device information, as applicable:
(i)

Orifice bore diameter (inches); or

(ii) Beta or area ratio, discharge coefficient, and other information necessary to calculate the flow rate;
(f) Relative density (specific gravity);
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(g) CO2 content (mole percent);
(h) N2 content (mole percent);
(i)

Heating value calculated under § 3175.125 (Btu/standard cubic feet);

(j)

Atmospheric pressure or elevation at the FMP;

(k) Pressure base;
(l)

Temperature base;

(m) Static-pressure tap location (upstream or downstream);
(n) Chart rotation (hours or days);
(o) Differential-pressure bellows range (inches of water);
(p) Static-pressure element range (psi); and
(q) For each chart or day integrated:
(i)

The time and date on and time and date off;

(ii) Average differential pressure (inches of water);
(iii) Average static pressure;
(iv) Static-pressure units of measure (psia or psig);
(v) Average temperature ( °F);
(vi) Integrator counts or extension;
(vii) Hours of flow; and
(viii) Volume (Mcf).

§ 3175.94 Volume determination.
(a) The volume for each chart integrated must be determined as follows:
V = IMV × IV
Where:
V = reported volume, Mcf
IMV = integral multiplier value, as calculated under this section
IV = the integral value determined by the integration process (also known as the “extension,” “integrated
extension,” and “integrator count”)
(1) If the primary device is a flange-tapped orifice plate, a single IMV must be calculated for each chart
or chart interval using the following equation:

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Where:
Cd = discharge coefficient or flow coefficient, calculated under API 14.3.3 or AGA Report No. 3 (1985), Section 5
(incorporated by reference, see § 3175.30)
β = Beta ratio
Y = gas expansion factor, calculated under API 14.3.3, Subsection 5.6 or AGA Report No. 3 (1985), Section 5
(incorporated by reference, see § 3175.30)
d = orifice diameter, in inches
Zb = supercompressibility at base pressure and temperature
Gr = relative density (specific gravity)
Zf = supercompressibility at flowing pressure and temperature
Tf = average flowing temperature, in degrees Rankine
(2) For other types of primary devices, the IMV must be calculated using the equations and procedures
recommended by the PMT and approved by the BLM, specific to the make, model, size, and area
ratio of the primary device being used.
(3) Variables that are functions of differential pressure, static pressure, or flowing temperature (e.g., Cd,
Y, Zf) must use the average values of differential pressure, static pressure, and flowing temperature
as determined from the integration statement and reported on the integration statement for the
chart or chart interval integrated. The flowing temperature must be the average flowing temperature
reported on the integration statement for the chart or chart interval being integrated.
(b) Atmospheric pressure used to convert static pressure in psig to static pressure in psia must be
determined under appendix A to this subpart.

§ 3175.100 Electronic gas measurement (secondary and tertiary device).
Except as stated in this section, as prescribed in Table 1 to this section, or grandfathered under § 3175.61, the
standards and requirements in this section apply to all EGM systems used at FMPs (Note: The following table lists
the standards in this subpart and the API standards that the operator must follow to install and maintain EGM
systems. A requirement applies when a column is marked with an “x” or a number.).

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§ 3175.101 Installation and operation of electronic gas measurement systems.
(a) Manifolds and gauge lines connecting the pressure taps to the secondary device must:
(1) Have a nominal diameter of not less than 3⁄8-inch, including ports and valves;
(2) Be sloped upwards from the pressure taps at a minimum pitch of 1 inch per foot of length with no
visible sag;
(3) Have the same internal diameter along their entire length;
(4) Not include tees except for the static-pressure line;
(5) Not be connected to any other devices or more than one differential pressure and static-pressure
transducer. If the operator is employing redundancy verification, two differential pressure and two
static-pressure transducers may be connected; and
(6) Be no longer than 6 feet.
(b) Each FMP must include a display, which must:
(1) Be readable without the need for data-collection units, laptop computers, a password, or any special
equipment;
(2) Be on site and in a location that is accessible to the AO;
(3) Include the units of measure for each required variable;
(4) Display the software version and previous-day's volume, as well as the following variables
consecutively:
(i)

Current flowing static pressure with units (psia or psig);

(ii) Current differential pressure (inches of water);
(iii) Current flowing temperature ( °F); and
(iv) Current flow rate (Mcf/day or scf/day); and
(5) Either display or post on site and accessible to the AO an hourly or daily QTR (see § 3175.104(a)) no
more than 31 days old showing the following information:
(i)

Previous-period (for this section, previous period means at least 1 day prior, but no longer than
1 month prior) average differential pressure (inches of water);

(ii) Previous-period average static pressure with units (psia or psig); and
(iii) Previous-period average flowing temperature ( °F).
(c) The following information must be maintained at the FMP in a legible condition, in compliance with §
3170.7(g) of this part, and accessible to the AO at all times:
(1) The unique meter ID number;
(2) Relative density (specific gravity);
(3) Elevation of the FMP;

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(4) Primary device information, such as orifice bore diameter (inches) or Beta or area ratio and
discharge coefficient, as applicable;
(5) Meter-tube mean inside diameter;
(6) Make, model, and location of approved isolating flow conditioners, if used;
(7) Location of the downstream end of 19-tube-bundle flow straighteners, if used;
(8) For self-contained EGM systems, make and model number of the system;
(9) For component-type EGM systems, make and model number of each transducer and the flow
computer;
(10) URL and upper calibrated limit for each transducer;
(11) Location of the static-pressure tap (upstream or downstream);
(12) Last primary-device inspection date; and
(13) Last secondary device verification date.
(d) The differential pressure, static pressure, and flowing temperature transducers must be operated between
the lower and upper calibrated limits of the transducer. The BLM may approve the differential pressure to
exceed the upper calibrated limit of the differential-pressure transducer for brief periods in plunger lift
operations; however, the differential pressure may not exceed the URL.
(e) The flowing temperature of the gas must be continuously measured and used in the flow-rate calculations
under API 21.1, Section 4 (incorporated by reference, see § 3175.30).

§ 3175.102 Verification and calibration of electronic gas measurement systems.
(a) Transducer verification and calibration after installation or repair.
(1) Before performing any verification required in this section, the operator must perform a leak test in
the manner prescribed in § 3175.92(a)(1).
(2) The operator must verify the points listed in API 21.1, Subsection 7.3.3 (incorporated by reference,
see § 3175.30), by comparing the values from the certified test device with the values used by the
flow computer to calculate flow rate. If any of these as-left readings vary from the test equipment
reading by more than the tolerance determined by API 21.1, Subsection 8.2.2.2, Equation 24
(incorporated by reference, see § 3175.30), then that transducer must be replaced and the new
transducer must be tested under this paragraph.
(3) For absolute static-pressure transducers, the value of atmospheric pressure used when the
transducer is vented to atmosphere must be calculated under appendix A to this subpart, measured
by a NIST-certified barometer with a stated accuracy of ±0.05 psi or better, or obtained from an
absolute-pressure calibration device.
(4) Before putting a meter into service, the differential-pressure transducer must be tested at zero with
full working pressure applied to both sides of the transducer. If the absolute value of the transducer
reading is greater than the reference accuracy of the transducer, expressed in inches of water
column, the transducer must be re-zeroed.
(b) Routine verification frequency.

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(1) If redundancy verification under paragraph (d) of this section is not used, the differential pressure,
static pressure, and temperature transducers must be verified under the requirements of paragraph
(c) of this section at the frequency specified in Table 1 to § 3175.100, in months; or
(2) If redundancy verification under paragraph (d) of this section is used, the differential pressure, static
pressure, and temperature transducers must be verified under the requirements of paragraph (d) of
this section. In addition, the transducers must be verified under the requirements of paragraph (c) of
this section at least annually.
(c) Routine verification procedures. Verifications must be performed according to API 21.1, Subsection 8.2
(incorporated by reference, see § 3175.30), with the following exceptions, additions, and clarifications:
(1) Before performing any verification required under this section, the operator must perform a leak test
consistent with § 3175.92(a)(1).
(2) An as-found verification for differential pressure, static pressure and temperature must be conducted
at the normal operating point of each transducer.
(i)

The normal operating point is the mean value taken over a previous time period not less than 1
day or greater than 1 month. Acceptable mean values include means weighted based on flow
time and flow rate.

(ii) For differential and static-pressure transducers, the pressure applied to the transducer for this
verification must be within five percentage points of the normal operating point. For example, if
the normal operating point for differential pressure is 17 percent of the upper calibrated limit,
the normal point verification pressure must be between 12 percent and 22 percent of the upper
calibrated limit.
(iii) For the temperature transducer, the water bath or test thermometer well must be within 20 °F of
the normal operating point for temperature.
(3) If any of the as-found values are in error by more than the manufacturer's specification for stability or
drift - as adjusted for static pressure and ambient temperature - on two consecutive verifications,
that transducer must be replaced prior to returning the meter to service.
(4) If a transducer is calibrated, the as-left verification must include the normal operating point of that
transducer, as defined in paragraph (c)(2) of this section.
(5) The as-found values for differential pressure obtained with the low side vented to atmospheric
pressure must be corrected to working-pressure values using API 21.1, Annex H, Equation H.1
(incorporated by reference, see § 3175.30).
(6) The verification tolerance for differential and static pressure is defined by API 21.1, Subsection
8.2.2.2, Equation 24 (incorporated by reference, see § 3175.30). The verification tolerance for
temperature is equivalent to the uncertainty of the temperature transmitter or 0.5 °F, whichever is
greater.
(7) All required verification points must be within the verification tolerance before returning the meter to
service.
(8) Before putting a meter into service, the differential-pressure transducer must be tested at zero with
full working pressure applied to both sides of the transducer. If the absolute value of the transducer
reading is greater than the reference accuracy of the transducer, expressed in inches of water
column, the transducer must be re-zeroed.
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(d) Redundancy verification procedures. Redundancy verifications must be performed as required under API
21.1, Subsection 8.2 (incorporated by reference, see § 3175.30), with the following exceptions, additions,
and clarifications:
(1) The operator must identify which set of transducers is used for reporting on the OGOR (the primary
transducers) and which set of transducers is used as a check (the check set of transducers);
(2) For every calendar month, the operator must compare the flow-time linear averages of differential
pressure, static pressure, and temperature readings from the primary transducers with those from
the check transducers;
(3)
(i)

If for any transducer the difference between the averages exceeds the tolerance defined by the
following equation:

Where:
Ap is the reference accuracy of the primary transducer and
Ac is the reference accuracy of the check transducer.
(ii) The operator must verify both the primary and check transducer under paragraph (c) of this
section within the first 5 days of the month following the month in which the redundancy
verification was performed. For example, if the redundancy verification for March reveals that
the difference in the flow-time linear averages of differential pressure exceeded the verification
tolerance, both the primary and check differential-pressure transducers must be verified under
paragraph (c) of this section by April 5th.
(e) The operator must retain documentation of each verification for the period required under § 3170.7 of this
part, including calibration data for transducers that were replaced, and submit it to the BLM upon request.
(1) For routine verifications, this documentation must include:
(i)

The information required in § 3170.7(g) of this part;

(ii) The time and date of the verification and the last verification date;
(iii) Primary device data (meter-tube inside diameter and differential-device size, Beta or area ratio);
(iv) The type and location of taps (flange or pipe, upstream or downstream static tap);
(v) The flow computer make and model;
(vi) The make and model number for each transducer, for component-type EGM systems;
(vii) Transducer data (make, model, differential, static, temperature URL, and upper calibrated limit);
(viii) The normal operating points for differential pressure, static pressure, and flowing temperature;
(ix) Atmospheric pressure;
(x) Verification points (as-found and applied) for each transducer;
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(xi) Verification points (as-left and applied) for each transducer, if calibration was performed;
(xii) The differential device inspection date and condition (e.g., clean, sharp edge, or surface
condition);
(xiii) Verification equipment make, model, range, accuracy, and last certification date;
(xiv) The name, contact information, and affiliation of the person performing the verification and any
witness, if applicable; and
(xv) Remarks, if any.
(2) For redundancy verification checks, this documentation must include;
(i)

The information required in § 3170.7(g) of this part;

(ii) The month and year for which the redundancy check applies;
(iii) The makes, models, upper range limits, and upper calibrated limits of the primary set of
transducers;
(iv) The makes, models, upper range limits, and upper calibrated limits of the check set of
transducers;
(v) The information required in API 21.1, Annex I (incorporated by reference, see § 3175.30);
(vii) The tolerance for differential pressure, static pressure, and temperature as calculated under
paragraph (d)(2) of this section; and
(viii) Whether or not each transducer required verification under paragraph (c) of this section.
(f) Notification of verification.
(1) For verifications performed after installation or following repair, the operator must notify the AO at
least 72 hours before conducting the verifications.
(2) For routine verifications, the operator must notify the AO at least 72 hours before conducting the
verification or submit a monthly or quarterly verification schedule to the AO in advance.
(g) If, during the verification, the combined errors in as-found differential pressure, static pressure, and
flowing temperature taken at the normal operating points tested result in a flow-rate error greater than 2
percent or 2 Mcf/day, whichever is greater, the volumes reported on the OGOR and on royalty reports
submitted to ONRR must be corrected beginning with the date that the inaccuracy occurred. If that date is
unknown, the volumes must be corrected beginning with the production month that includes the date that
is half way between the date of the last verification and the date of the present verification. See the
example in § 3175.92(f).
(h) Test equipment requirements.
(1) Test equipment used to verify or calibrate transducers at an FMP must be certified at least every 2
years. Documentation of the certification must be on site and made available to the AO during all
verifications and must show:
(i)

The test equipment serial number, make, and model;

(ii) The date on which the recertification took place;
(iii) The range of the test equipment; and
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(iv) The uncertainty determined or verified as part of the recertification.
(2) Test equipment used to verify or calibrate transducers at an FMP must meet the following accuracy
standards:
(i)

The accuracy of the test equipment, stated in actual units of measure, must be no greater than
0.5 times the reference accuracy of the transducer being verified, also stated in actual units of
measure; or

(ii) The equipment must have a stated accuracy of at least 0.10 percent of the upper calibrated
limit of the transducer being verified.

§ 3175.103 Flow rate, volume, and average value calculation.
(a) The flow rate must be calculated as follows:
(1) For flange-tapped orifice plates, the flow rate must be calculated under:
(i)

API 14.3.3, Section 4 and API 14.3.3, Section 5 (incorporated by reference, see § 3175.30); and

(ii) AGA Report No. 8 (incorporated by reference, see § 3175.30), for supercompressibility.
(2) For primary devices other than flange-tapped orifice plates, for which there are no industry standards,
the flow rate must be calculated under the equations and procedures recommended by the PMT and
approved by the BLM, specific to the make, model, size, and area ratio of the primary device used.
(b) Atmospheric pressure used to convert static pressure in psig to static pressure in psia must be
determined under API 21.1, Subsection 8.3.3 (incorporated by reference, see § 3175.30).
(c) Hourly and daily gas volumes, average values of the live input variables, flow time, and integral value or
average extension as required under § 3175.104 must be determined under API 21.1, Section 4 and API
21.1, Annex B (incorporated by reference, see § 3175.30).

§ 3175.104 Logs and records.
(a) The operator must retain, and submit to the BLM upon request, the original, unaltered, unprocessed, and
unedited daily and hourly QTRs, which must contain the information identified in API 21.1, Subsection 5.2
(incorporated by reference, see § 3175.30), with the following additions and clarifications:
(1) The information required in § 3170.7(g) of this part;
(2) The volume, flow time, and integral value or average extension must be reported to at least 5 decimal
places. The average differential pressure, static pressure, and temperature as calculated in §
3175.103(c), must be reported to at least three decimal places; and
(3) A statement of whether the operator has submitted the integral value or average extension.
(b) The operator must retain, and submit to the BLM upon request, the original, unaltered, unprocessed, and
unedited configuration log, which must contain the information specified in API 21.1, Subsection 5.4
(including the flow-computer snapshot report in API 21.1, Subsection 5.4.2), and API 21.1, Annex G
(incorporated by reference, see § 3175.30), with the following additions and clarifications:
(1) The information required in § 3170.7(g) of this part;
(2) Software/firmware identifiers under API 21.1, Subsection 5.3 (incorporated by reference, see §
3175.30);
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(3) For very-low-volume FMPs only, the fixed temperature, if not continuously measured ( °F); and
(4) The static-pressure tap location (upstream or downstream).
(c) The operator must retain, and submit to the BLM upon request, the original, unaltered, unprocessed, and
unedited event log. The event log must comply with API 21.1, Subsection 5.5 (incorporated by reference,
see § 3175.30), with the following additions and clarifications: The event log must have sufficient capacity
and must be retrieved and stored at intervals frequent enough to maintain a continuous record of events
as required under § 3170.7 of this part, or the life of the FMP, whichever is shorter.
(d) The operator must retain an alarm log and provide it to the BLM upon request. The alarm log must comply
with API 21.1, Subsection 5.6 (incorporated by reference, see § 3175.30).
(e) Records may only be submitted from accounting system names and versions and flow computer makes
and models that have been approved by the BLM (see § 3175.49).

§ 3175.110 Gas sampling and analysis.
Except as stated in this section or as prescribed in Table 1 to this section, the standards and requirements in this
section apply to all gas sampling and analyses. (Note: The following table lists the standards in this subpart and the
API standards that the operator must follow to take a gas sample, analyze the gas sample, and report the findings
of the gas analysis. A requirement applies when a column is marked with an “x” or a number.)

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§ 3175.111 General sampling requirements.
(a) Samples must be taken by one of the following methods:
(1) Spot sampling under §§ 3175.113 through 3175.115;
(2) Flow-proportional composite sampling under § 3175.116; or
(3) On-line gas chromatograph under § 3175.117.
(b) At all times during the sampling process, the minimum temperature of all gas sampling components must
be the lesser of:
(1) The flowing temperature of the gas measured at the time of sampling; or
(2) 30 °F above the calculated hydrocarbon dew point of the gas.

§ 3175.112 Sampling probe and tubing.
(a) All gas samples must be taken from a sample probe that complies with the requirements of paragraphs
(b) and (c) of this section.
(b) Location of sample probe.
(1) The sample probe must be located in the meter tube in accordance with API 14.1, Subsection 6.4.2
(incorporated by reference, see § 3175.30), and must be the first obstruction downstream of the
primary device.
(2) The sample probe must be exposed to the same ambient temperature as the primary device. The
operator may accomplish this by physically locating the sample probe in the same ambient
temperature conditions as the primary device (such as in a heated meter house) or by installing
insulation and/or heat tracing along the entire meter run. If the operator chooses to use insulation to
comply with this requirement, the AO may prescribe the quality of the insulation based on site
specific factors such as ambient temperature, flowing temperature of the gas, composition of the
gas, and location of the sample probe in relation to the orifice plate (i.e., inside or outside of a meter
house).
(c) Sample probe design and type.
(1) Sample probes must be constructed from stainless steel.
(2) If a regulating type of sample probe is used, the pressure-regulating mechanism must be inside the
pipe or maintained at a temperature of at least 30 °F above the hydrocarbon dew point of the gas.
(3) The sample probe length must be the shorter of:
(i)

The length necessary to place the collection end of the probe in the center one third of the pipe
cross-section; or

(ii) The recommended length of the probe in Table 1 in API 14.1, Subsection 6.4 (incorporated by
reference, see § 3175.30).
(4) The use of membranes, screens, or filters at any point in the sample probe is prohibited.
(d) Sample tubing connecting the sample probe to the sample container or analyzer must be constructed of
stainless steel or nylon 11.
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§ 3175.113 Spot samples - general requirements.
(a) If an FMP is not flowing at the time that a sample is due, a sample must be taken within 15 days after flow
is re-initiated. Documentation of the non-flowing status of the FMP must be entered into GARVS as
required under § 3175.120(f).
(b) The operator must notify the AO at least 72 hours before obtaining a spot sample as required by this
subpart, or submit a monthly or quarterly schedule of spot samples to the AO in advance of taking
samples.
(c) Sample cylinder requirements. Sample cylinders must:
(1) Comply with API 14.1, Subsection 9.1 (incorporated by reference, see § 3175.30);
(2) Have a minimum capacity of 300 cubic centimeters; and
(3) Be cleaned before sampling under GPA 2166-05, Appendix A (incorporated by reference, see §
3175.30), or an equivalent method. The operator must maintain documentation of cleaning (see §
3170.7), have the documentation available on site during sampling, and provide it to the BLM upon
request.
(d) Spot sampling using portable gas chromatographs.
(1) Sampling separators, if used, must:
(i)

Be constructed of stainless steel;

(ii) Be cleaned under GPA 2166-05, Appendix A (incorporated by reference, see § 3175.30), or an
equivalent method, prior to sampling. The operator must maintain documentation of cleaning
(see § 3170.7), have the documentation available on site during sampling, and provide it to the
BLM upon request; and
(iii) Be operated under GPA 2166-05, Appendix B.3 (incorporated by reference, see § 3175.30).
(2) The sample port and inlet to the sample line must be purged using the gas being sampled before
completing the connection between them.
(3) The portable GC must be operated, verified, and calibrated under § 3175.118.
(4) The documentation of verification or calibration required in § 3175.118(d) must be available for
inspection by the BLM at the time of sampling.
(5) Minimum number of samples and analyses.
(i)

For low- and very-low-volume FMPs, at least three samples must be taken and analyzed;

(ii) For high-volume FMPs, samples must be taken and analyzed until the difference between the
maximum heating value and minimum heating value calculated from three consecutive
analyses is less than or equal to 16 Btu/scf;
(iii) For very-high-volume FMPs, samples must be taken and analyzed until the difference between
the maximum heating value and minimum heating value calculated from three consecutive
analyses is less than or equal to 8 Btu/scf.
(6) The heating value and relative density used for OGOR reporting must be:

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(i)

43 CFR 3175.113(d)(6)(i)

The mean heating value and relative density calculated from the three analyses required in
paragraph (d)(5) of this section;

(ii) The median heating value and relative density calculated from the three analyses required in
paragraph (d)(5) of this section; or
(iii) Any other method approved by the BLM.

§ 3175.114 Spot samples - allowable methods.
(a) Spot samples must be obtained using one of the following methods:
(1) Purging - fill and empty method. Samples taken using this method must comply with GPA 2166-05,
Section 9.1 (incorporated by reference, see § 3175.30);
(2) Helium “pop” method. Samples taken using this method must comply with GPA 2166-05, Section 9.5
(incorporated by reference, see § 3175.30). The operator must maintain documentation
demonstrating that the cylinder was evacuated and pre-charged before sampling and make the
documentation available to the AO upon request;
(3) Floating piston cylinder method. Samples taken using this method must comply with GPA 2166-05,
Sections 9.7.1 to 9.7.3 (incorporated by reference, see § 3175.30). The operator must maintain
documentation of the seal material and type of lubricant used and make the documentation
available to the AO upon request;
(4) Portable gas chromatograph. Samples taken using this method must comply with § 3175.118; or
(5) Other methods approved by the BLM (through the PMT) and posted at www.blm.gov.
(b) If the operator uses either a purging - fill and empty method or a helium “pop” method, and if the flowing
pressure at the sample port is less than or equal to 15 psig, the operator may also employ a vacuumgathering system. Samples taken using a vacuum-gathering system must comply with API 14.1,
Subsection 11.10 (incorporated by reference, see § 3175.30), and the samples must be obtained from the
discharge of the vacuum pump.

§ 3175.115 Spot samples - frequency.
(a) Unless otherwise required under paragraph (b) of this section, spot samples for all FMPs must be taken
and analyzed at the frequency (once during every period, stated in months) prescribed in Table 1 to §
3175.110.
(b) After the time frames listed in paragraph (b)(1) of this section, the BLM may change the required sampling
frequency for high-volume and very-high-volume FMPs if the BLM determines that the sampling frequency
required in Table 1 in § 3175.110 is not sufficient to achieve the heating value uncertainty levels required
in § 3175.31(b).
(1) Timeframes for implementation.
(i)

For high-volume FMPs, the BLM may change the sampling frequency no sooner than 2 years
after the FMP begins measuring gas or January 19, 2021, whichever is later; and

(ii) For very-high-volume FMPs, the BLM may change the sampling frequency or require compliance
with paragraph (b)(5) of this section no sooner than 1 year after the FMP begins measuring gas
or January 17, 2020, whichever is later.

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(2) The BLM will calculate the new sampling frequency needed to achieve the heating value uncertainty
levels required in § 3175.31(b). The BLM will base the sampling frequency calculation on the heating
value variability. The BLM will notify the operator of the new sampling frequency.
(3) The new sampling frequency will remain in effect until the heating value variability justifies a different
frequency.
(4) The new sampling frequency will not be more frequent than once every 2 weeks nor less frequent
than once every 6 months.
(5) For very-high-volume FMPs, the BLM may require the installation of a composite sampling system or
on-line GC if the heating value uncertainty levels in § 3175.31(b) cannot be achieved through spot
sampling. Composite sampling systems or on-line gas chromatographs that are installed and
operated in accordance with this section comply with the uncertainty requirement of §
3175.31(b)(2).
(c) The time between any two samples must not exceed the timeframes shown in Table 1 to this section.

(d) If a composite sampling system or an on-line GC is installed under § 3175.116 or § 3175.117, either on
the operator's own initiative or in response to a BLM order for a very-high-volume FMP under paragraph
(b)(5) of this section, it must be installed and operational no more than 30 days after the due date of the
next sample.
(e) The required sampling frequency for an FMP at which a composite sampling system or an on-line gas
chromatograph is removed from service is prescribed in paragraph (a) of this section.
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§ 3175.116 Composite sampling methods.
(a) Composite samplers must be flow-proportional.
(b) Samples must be collected using a positive-displacement pump.
(c) Sample cylinders must be sized to ensure the cylinder capacity is not exceeded within the normal
collection frequency.

§ 3175.117 On-line gas chromatographs.
(a) On-line GCs must be installed, operated, and maintained under GPA 2166-05, Appendix D (incorporated by
reference, see § 3175.30), and the manufacturer's specifications, instructions, and recommendations.
(b) The GC must comply with the verification and calibration requirements of § 3175.118. The results of all
verifications must be submitted to the AO upon request.
(c) Upon request, the operator must submit to the AO the manufacturer's specifications and installation and
operational recommendations.

§ 3175.118 Gas chromatograph requirements.
(a) All GCs must be installed, operated, and calibrated under GPA 2261-13 (incorporated by reference, see §
3175.30).
(b) Samples must be analyzed until the un-normalized sum of the mole percent of all gases analyzed is
between 97 and 103 percent.
(c) A GC may not be used to analyze any sample from an FMP until the verification meets the standards of
this paragraph (c).
(1) GCs must be verified under GPA 2261-13, Section 6 (incorporated by reference, see § 3175.30), not
less than once every 7 days.
(2) All gases used for verification and calibration must meet the standards of GPA 2198-03, Sections 3
and 4 (incorporated by reference, see § 3175.30).
(3) All new gases used for verification and calibration must be authenticated prior to verification or
calibration under the standards of GPA 2198-03, Section 5 (incorporated by reference, see §
3175.30).
(4) The gas used to calibrate a GC must be maintained under Section 6 of GPA 2198-03 (incorporated by
reference, see § 3175.30).
(5) If the composition of the gas used for verification as determined by the GC varies from the certified
composition of the gas used for verification by more than the reproducibility values listed in GPA
2261-13, Section 10 (incorporated by reference, see § 3175.30), the GC must be calibrated under
GPA 2261-13, Section 6 (incorporated by reference, see § 3175.30).
(6) If the GC is calibrated, it must be re-verified under paragraph (c)(5) of this section.
(d) The operator must retain documentation of the verifications for the period required under § 3170.6 of this
part, and make it available to the BLM upon request. The documentation must include:
(1) The components analyzed;
(2) The response factor for each component;
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(3) The peak area for each component;
(4) The mole percent of each component as determined by the GC;
(5) The mole percent of each component in the gas used for verification;
(6) The difference between the mole percents determined in paragraphs (d)(4) and (5) of this section,
expressed in relative percent;
(7) Evidence that the gas used for verification and calibration:
(i)

Meets the requirements of paragraph (c)(2) of this section, including a unique identification
number of the calibration gas used, the name of the supplier of the calibration gas, and the
certified list of the mole percent of each component in the calibration gas;

(ii) Was authenticated under paragraph (c)(3) of this section prior to verification or calibration,
including the fidelity plots; and
(iii) Was maintained under paragraph (c)(4) of this section, including the fidelity plot made as part
of the calibration run;
(8) The chromatograms generated during the verification process;
(9) The time and date the verification was performed; and
(10) The name and affiliation of the person performing the verification.
(e) Extended analyses must be taken in accordance with GPA 2286-14 (incorporated by reference, see §
3175.30) or other method approved by the BLM.

§ 3175.119 Components to analyze.
(a) The gas must be analyzed for the following components:
(1) Methane;
(2) Ethane;
(3) Propane;
(4) Iso Butane;
(5) Normal Butane;
(6) Pentanes;
(7) Hexanes + (C6+);
(8) Carbon dioxide; and
(9) Nitrogen.
(b) When the concentration of C6+ exceeds 0.5 mole percent, the following gas components must also be
analyzed:
(1) Hexanes;
(2) Heptanes;
(3) Octanes; and
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(4) Nonanes +.
(c) In lieu of testing each sample for the components required under paragraph (b) of this section, the
operator may periodically test for these components and adjust the assumed C6+ composition to remove
bias in the heating value (see § 3175.126(a)(3)). The C6+ composition must be applied to the mole
percent of C6+ analyses until the next analysis is done under paragraph (b) of this section. The minimum
analysis frequency for the components listed in paragraph (b) of this section is as follows:
(1) For high-volume FMPs, once per year; and
(2) For very-high-volume FMPs, once every 6 months.

§ 3175.120 Gas analysis report requirements.
(a) The gas analysis report must contain the following information:
(1) The information required in § 3170.7(g) of this part;
(2) The date and time that the sample for spot samples was taken or, for composite samples, the date
the cylinder was installed and the date the cylinder was removed;
(3) The date and time of the analysis;
(4) For spot samples, the effective date, if other than the date of sampling;
(5) For composite samples, the effective start and end date;
(6) The name of the laboratory where the analysis was performed;
(7) The device used for analysis (i.e., GC, calorimeter, or mass spectrometer);
(8) The make and model of analyzer;
(9) The date of last calibration or verification of the analyzer;
(10) The flowing temperature at the time of sampling;
(11) The flowing pressure at the time of sampling, including units of measure (psia or psig);
(12) The flow rate at the time of sampling;
(13) The ambient air temperature at the time of sampling;
(14) Whether or not heat trace or any other method of heating was used;
(15) The type of sample (i.e., spot-cylinder, spot-portable GC, composite);
(16) The sampling method if spot-cylinder (e.g., fill and empty, helium pop);
(17) A list of the components of the gas tested;
(18) The un-normalized mole percents of the components tested, including a summation of those mole
percents;
(19) The normalized mole percent of each component tested, including a summation of those mole
percents;
(20) The ideal heating value (Btu/scf);
(21) The real heating value (Btu/scf), dry basis;
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(22) The hexane+ split, if applicable;
(23) The pressure base and temperature base;
(24) The relative density; and
(25) The name of the company obtaining the gas sample.
(b) Components that are listed on the analysis report, but not tested, must be annotated as such.
(c) The heating value and relative density must be calculated under API 14.5 (incorporated by reference, see §
3175.30).
(d) The base supercompressibility must be calculated under AGA Report No. 8 (incorporated by reference,
see § 3175.30).
(e) The operator must submit all gas analysis reports to the BLM within 15 days of the due date for the
sample as specified in § 3175.115.
(f) Unless a variance is granted, the operator must submit all gas analysis reports and other required related
information electronically through the GARVS. The BLM will grant a variance to the electronic-submission
requirement only in cases where the operator demonstrates that it is a small business, as defined by the
U.S. Small Business Administration, and does not have access to the Internet.

§ 3175.121 Effective date of a spot or composite gas sample.
(a) Unless otherwise specified on the gas analysis report, the effective date of a spot sample is the date on
which the sample was taken.
(b) The effective date of a spot gas sample may be no later than the first day of the production month
following the operator's receipt of the laboratory analysis of the sample.
(c) Unless otherwise specified on the gas analysis report, the effective date of a composite sample is the first
of the month in which the sample was removed.
(d) The provisions of this section apply only to OGORs, QTRs, and gas sample reports generated after January
17, 2017.

§ 3175.125 Calculation of heating value and volume
(a) The heating value of the gas sampled must be calculated as follows:
(1) Gross heating value is defined by API 14.5, Subsection 3.7 (incorporated by reference, see § 3175.30)
and must be calculated under API 14.5, Subsection 7.1 (incorporated by reference, see § 3175.30);
and
(2) Real heating value must be calculated by dividing the gross heating value of the gas calculated under
paragraph (a)(1) of this section by the compressibility factor of the gas at 14.73 psia and 60 °F.
(b) Average heating value determination.
(1) If a lease, unit PA, or CA has more than one FMP, the average heating value for the lease, unit PA, or
CA for a reporting month must be the volume-weighted average of heating values, calculated as
follows:

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(2) If the effective date of a heating value for an FMP is other than the first day of the reporting month,
the average heating value of the FMP must be the volume-weighted average of heating values,
determined as follows:

Where:
HVi = the heating value for FMPi, in Btu/scf
HVi,j = the heating value for FMPi, for partial month j, in Btu/scf
Vi,j = the volume measured by FMPi, for partial month j, in Btu/scf
Subscript i represents each FMP for the lease, unit PA, or CA
Subscript j represents a partial month for which heating value HVi,j is effective
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m = the number of different heating values in a reporting month for an FMP
(c) The volume must be determined under § 3175.94 (mechanical recorders) or § 3175.103(c) (EGM
systems).

§ 3175.126 Reporting of heating value and volume.
(a) The gross heating value and real heating value, or average gross heating value and average real heating
value, as applicable, derived from all samples and analyses must be reported on the OGOR in units of Btu/
scf under the following conditions:
(1) Containing no water vapor (“dry”), unless the water vapor content has been determined through
actual on-site measurement and reported on the gas analysis report. The heating value may not be
reported on the basis of an assumed water-vapor content. Acceptable methods of measuring water
vapor are:
(i)

Chilled mirror;

(ii) Laser detectors; and
(iii) Other methods approved by the BLM;
(2) Adjusted to a pressure of 14.73 psia and a temperature of 60 °F; and
(3) For samples analyzed under § 3175.119(a), and notwithstanding any provision of a contract between
the operator and a purchaser or transporter, the composition of hexane+ is deemed to be:
(i)

60 percent n-hexane, 30 percent n-heptane, and 10 percent n-octane; or

(ii) The composition determined under § 3175.119(c).
(b) The volume for royalty purposes must be reported on the OGOR in units of Mcf as follows:
(1) The volume must not be adjusted for water-vapor content or any other factors that are not included
in the calculations required in § 3175.94 or § 3175.103; and
(2) The volume must match the monthly volume(s) shown in the unedited QTR(s) or integration
statement(s) unless edits to the data are documented under paragraph (c) of this section.
(c) Edits and adjustments to reported volume or heating value.
(1) If for any reason there are measurement errors stemming from an equipment malfunction that
results in discrepancies to the calculated volume or heating value of the gas, the volume or heating
value reported during the period in which the volume or heating value error persisted must be
estimated.
(2) All edits made to the data before the submission of the OGOR must be documented and include
verifiable justifications for the edits made. This documentation must be maintained under § 3170.7
of this part and must be submitted to the BLM upon request.
(3) All values on daily and hourly QTRs that have been changed or edited must be clearly identified and
must be cross referenced to the justification required in paragraph (c)(2) of this section.

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(4) The volumes reported on the OGOR must be corrected beginning with the date that the inaccuracy
occurred. If that date is unknown, the volumes must be corrected beginning with the production
month that includes the date that is half way between the date of the previous verification and the
most recent verification date.

§ 3175.130 Transducer testing protocol.
The BLM will approve a particular make, model, and range of differential-pressure, static-pressure, or temperature
transducer for use in an EGM system only if the testing performed on the transducer met all of the standards and
requirements stated in §§ 3175.131 through 3175.135.

§ 3175.131 General requirements for transducer testing.
(a) All testing must be performed by a qualified test facility.
(b) Number and selection of transducers tested.
(1) A minimum of five transducers of the same make, model, and URL, selected at random from the
stock used to supply normal field operations, must be type-tested.
(2) The serial number of each transducer selected must be documented. The date, location, and batch
identifier, if applicable, of manufacture must be ascertainable from the serial number.
(3) For the purpose of this section, the term “model” refers to the base model number on which the BLM
determines the transducer performance. For example: A manufacturer makes a transmitter with a
model number 1234-XYZ, where “1234” identifies the transmitter cell, “X” identifies the output type,
“Y” identifies the mounting type, and “Z” identifies where the static pressure is taken. The testing
under this section would only be required on the base model number (“1234”), assuming that “X”, “Y”,
or “Z” does not affect the performance of the transmitter.
(4) For multi-variable transducers, each cell URL must be tested only once under this section. For
example: A manufacturer of a transducer measuring both differential and static pressure makes a
model with available differential-pressure URLs of 100 inches, 500 inches, and 1,000 inches, and
static-pressure URLs of 250 psia, 1,000 psia, and 2,500 psia. Although there are nine possible
combinations of differential-pressure and static-pressure URLs, only six tests are required to cover
each cell URL.
(c) Test conditions - general. The electrical supply must meet the following minimum tolerances:
(1) Rated voltage: ±1 percent uncertainty;
(2) Rated frequency: ±1 percent uncertainty;
(3) Alternating current harmonic distortion: Less than 5 percent; and
(4) Direct current ripple: Less than 0.10 percent uncertainty.
(d) The input and output (if the output is analog) of each transducer must be measured with equipment that
has a published reference uncertainty less than or equal to 25 percent of the published reference
uncertainty of the transducer under test across the measurement range common to both the transducer
under test and the test instrument. Reference uncertainty for both the test instrument and the transducer
under test must be expressed in the units the transducer measures to determine acceptable uncertainty.
For example, if the transducer under test has a published reference uncertainty of ±0.05 percent of span,

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and a span of 0 to 500 psia, then this transducer has a reference accuracy of ±0.25 psia (0.05 percent of
500 psia). To meet the requirements of this paragraph (d), the test instrument in this example must have
an uncertainty of ±0.0625 psia or less (25 percent of ±0.25 psia).
(e) If the manufacturer's performance specifications for the transducer under test include corrections made
by an external device (such as linearization), then the external device must be tested along with the
transducer and be connected to the transducer in the same way as in normal field operations.
(f) If the manufacturer specifies the extent to which the measurement range of the transducer under test may
be adjusted downward (i.e., spanned down), then each test required in §§ 3175.132 and 3175.133 must
be carried out at least at both the URL and the minimum upper calibrated limit specified by the
manufacturer. For upper calibrated limits between the maximum and the minimum span that are not
tested, the BLM will use the greater of the uncertainties measured at the maximum and minimum spans
in determining compliance with the requirements of § 3175.31(a).
(g) After initial calibration, no calibration adjustments to the transducer may be made until all required tests in
§§ 3175.132 and 3175.133 are completed.
(h) For all of the testing required in §§ 3175.132 and 3175.133, the term “tested for accuracy” means a
comparison between the output of the transducer under test and the test equipment taken as follows:
(1) The following values must be tested in the order shown, expressed as a percent of the transducer
span:
(i)

(Ascending values) 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100; and

(ii) (Descending values) 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, and 0.
(2) If the device under test is an absolute-pressure transducer, the “0” values listed in paragraphs
(h)(1)(i) and (ii) of this section must be replaced with “atmospheric pressure at the test facility;”
(3) Input approaching each required test point must be applied asymptotically without overshooting the
test point;
(4) The comparison of the transducer and the test equipment measurements must be recorded at each
required point; and
(5) For static-pressure transducers, the following test point must be included for all tests:
(i)

For gauge-pressure transducers, a gauge pressure of −5 psig; and

(ii) For absolute-pressure transducers, an absolute pressure of 5 psia.

§ 3175.132 Testing of reference accuracy.
(a) The following reference test conditions must be maintained for the duration of the testing:
(1) Ambient air temperature must be between 59 °F and 77 °F and must not vary over the duration of the
test by more than ±2 °F;
(2) Relative humidity must be between 45 percent and 75 percent and must not vary over the duration of
the test by more than ±5 percent;
(3) Atmospheric pressure must be between 12.46 psi and 15.36 psi and must not vary over the duration
of the test by more than ±0.2 psi;
(4) The transducer must be isolated from any externally induced vibrations;
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(5) The transducer must be mounted according to the manufacturer's specifications in the same manner
as it would be mounted in normal field operations;
(6) The transducer must be isolated from any external electromagnetic fields; and
(7) For reference accuracy testing of differential-pressure transducers, the downstream side of the
transducer must be vented to the atmosphere.
(b) Before reference testing begins, the following pre-conditioning steps must be followed:
(1) After power is applied to the transducer, it must be allowed to stabilize for at least 30 minutes before
applying any input pressure or temperature;
(2) The transducer must be exercised by applying three full-range traverses in each direction; and
(3) The transducer must be calibrated according to manufacturer specifications if a calibration is
required or recommended by the manufacturer.
(c) Immediately following preconditioning, the transducer must be tested at least three times for accuracy
under § 3175.131(h). The results of these tests must be used to determine the transducer's reference
accuracy under § 3175.135.

§ 3175.133 Testing of influence effects.
(a) General requirements.
(1) Reference conditions (see § 3175.132), with the exception of the influence effect being tested under
this section, must be maintained for the duration of these tests.
(2) After completing the required tests for each influence effect under this section, the transducer under
test must be returned to reference conditions and tested for accuracy under § 3175.132.
(b) Ambient temperature.
(1) The transducer's accuracy must be tested at the following temperatures ( °F): +68, +104, +140, + 68,
0, −4, −40, +68.
(2) The ambient temperature must be held to ±4 °F from each required temperature during the accuracy
test at each point.
(3) The rate of temperature change between tests must not exceed 2 °F per minute.
(4) The transducer must be allowed to stabilize at each test temperature for at least 1 hour.
(5) For each required temperature test point listed in this paragraph, the transducer must be tested for
accuracy under § 3175.131(h).
(c) Static-pressure effects (differential-pressure transducers only).
(1) For single-variable transducers, the following pressures must be applied equally to both sides of the
transducer, expressed in percent of maximum rated working pressure: 0, 50, 100, 75, 25, 0.
(2) For multivariable transducers, the following pressures must be applied equally to both sides of the
transducer, expressed in percent of the URL of the static-pressure transducer: 0, 50, 100, 75, 25, 0.
(3) For each point required in paragraphs (c)(1) and (2) of this section, the transducer must be tested for
accuracy under § 3175.131(h).
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(d) Mounting position effects. The transducer must be tested for accuracy at four different orientations under
§ 3175.131(h) as follows:
(1) At an angle of −10° from a vertical plane;
(2) At an angle of +10° from a vertical plane;
(3) At an angle of −10° from a vertical plane perpendicular to the vertical plane required in paragraphs
(d)(1) and (2) of this section; and
(4) At an angle of +10° from a vertical plane perpendicular to the vertical plane required in paragraphs
(d)(1) and (2) of this section.
(e) Over-range effects.
(1) A pressure of 150 percent of the URL, or to the maximum rated working pressure of the transducer,
whichever is less, must be applied for at least 1 minute.
(2) After removing the applied pressure, the transducer must be tested for accuracy under §
3175.131(h).
(3) No more than 5 minutes must be allowed between performing the procedures described in
paragraphs (e)(1) and (2) of this section.
(f) Vibration effects.
(1) An initial resonance test must be conducted by applying the following test vibrations to the
transducer along each of the three major axes of the transducer while measuring the output of the
transducer with no pressure applied:
(i)

The amplitude of the applied test frequency must be at least 0.35mm below 60 Hertz (Hz) and
49 meter per second squared (m/s2) above 60 Hz; and

(ii) The applied frequency must be swept from 10 Hz to 2,000 Hz at a rate not greater than 0.5
octaves per minute.
(2) After the initial resonance search, an endurance conditioning test must be conducted as follows:
(i)

Twenty frequency sweeps from 10 Hz to 2,000 Hz to 10 Hz must be applied to the transducer at
a rate of 1 octave per minute, repeated for each of the 3 major axes; and

(ii) The measurement of the transducer's output during this test is unnecessary.
(3) A final resonance test must be conducted under paragraph (f)(1) of this section.

§ 3175.134 Transducer test reporting.
(a) Each test required by §§ 3175.131 through 3175.133 must be fully documented by the test facility
performing the tests. The report must indicate the results for each required test and include all data
points recorded.
(b) The report must be submitted to the PMT. If the PMT determines that all testing was completed as
required by §§ 3175.131 through 3175.133, it will make a recommendation that the BLM approve the
transducer make, model, and range, along with the reference uncertainty, influence effects, and any
operating restrictions, and posts them to the BLM's website at www.blm.gov as an approved device.

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§ 3175.135 Uncertainty determination.
(a) Reference uncertainty calculations for each transducer of a given make, model, URL, and turndown must
be determined as follows (the result for each transducer is denoted by the subscript i):
(1) Maximum error (Ei). The maximum error for each transducer is the maximum difference between any
input value from the test device and the corresponding output from the transducer under test for any
required test point, and must be expressed in percent of transducer span.
(2) Hysteresis (Hi). The testing required in § 3175.132 requires at least three pairs of tests using both
ascending test points (low to high) and descending test points (high to low) of the same value.
Hysteresis is the maximum difference between the ascending value and the descending value for
any single input test value of a test pair. Hysteresis must be expressed in percent of span.
(3) Repeatability (Ri). The testing required under § 3175.132 requires at least three pairs of tests using
both ascending test points (low to high) and descending test points (high to low) of the same value.
Repeatability is the maximum difference between the value of any of the three ascending test points
for a given input value or of the three descending test points for a given value. Repeatability must be
expressed in percent of span.
(b) Reference uncertainty of a transducer. The reference uncertainty of each transducer of a given make,
model, URL, and turndown (Ur,i) must be determined as follows:

Where Ei, Hi, and Ri, are described in paragraph (a) of this section. Reference uncertainty is expressed in
percent of span.
(c) Reference uncertainty for the make, model, URL, and turndown of a transducer (Ur) must be determined as
follows:
Ur = s × tdist
Where:
s = the standard deviation of the reference uncertainties determined for each transducer (Ur,i)
tdist = the “t-distribution” constant as a function of degrees of freedom (n-1) and at a 95 percent confidence
level, where n = the number of transducers of a specific make, model, URL, and turndown tested (minimum of
5)
(d) Influence effects. The uncertainty from each influence effect required to be tested under § 3175.133 must
be determined as follows:
(1) Zero-based errors of each transducer. Zero-based errors from each influence test must be
determined as follows:

Where:
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subscript i represents the results for each transducer tested of a given make, model, URL, and turndown
subscript n represents the results for each influence effect test required under § 3175.133
Ezero,n,i = Zero-based error for influence effect n, for transducer i, in percent of span per increment of influence
effect
Mn = the magnitude of influence effect n (e.g., 1,000 psi for static-pressure effects, 50 °F for ambient
temperature effects)
And:
DZn,i = Zn,i−Zref ,i
Where:
Zn,i = the average output from transducer i with zero input from the test device, during the testing of influence
effect n
Zref,i = the average output from transducer i with zero input from the test device, during reference testing.
(2) Span-based errors of each transducer. Span-based errors from each influence effect must be
determined as follows:

Where:
Espan,n,i = Span-based error for influence effect n, for transducer i, in percent of reading per increment of
influence effect
Sn,i = the average output from transducer i, with full span applied from the test device, during the testing for
influence effect n.
(3) Zero- and span-based errors due to influence effects for a make, model, URL, and turndown of a
transducer must be determined as follows:
Ez,n = sz,n ×tdist
Es,n = ss,n × tdist
Where:
Ez,n = the zero-based error for a make, model, URL, and turndown of transducer, for influence effect n, in percent
of span per unit of magnitude for the influence effect
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Es,n = the span-based error for a make, model, URL, and turndown of transducer, for influence effect n, in
percent of reading per unit of magnitude for the influence effect
sz,n = the standard deviation of the zero-based differences from the influence effect tests under § 3175.133
and the reference uncertainty tests, in percent
ss,n = the standard deviation of the span-based differences from the influence effect tests under § 3175.133
and the reference uncertainty tests, in percent
tdist = the “t-distribution” constant as a function of degrees of freedom (n-1) and at a 95 percent confidence
level, where n = the number of transducers of a specific make, model, URL, and turndown tested (minimum of
5).

§ 3175.140 Flow-computer software testing.
The BLM will approve a particular version of flow-computer software for use in a specific make and model of flow
computer only if the testing performed on the software meets all of the standards and requirements in §§ 3175.141
through 3175.144. Type-testing is required for each software version that affects the calculation of flow rate,
volume, heating value, live input variable averaging, flow time, or the integral value. Software updates or changes
that do not affect these items do not require BLM approval.

§ 3175.141 General requirements for flow-computer software testing.
(a) Test facility. All testing must be performed by a qualified test facility not affiliated with the flow-computer
manufacturer.
(b) Selection of flow-computer software to be tested.
(1) Each software version tested must be identical to the software version installed at FMPs for normal
field operations.
(2) Each software version must have a unique identifier.
(c) Testing method. Input variables may be either:
(1) Applied directly to the hardware registers; or
(2) Applied physically to a transducer. If input variables are applied physically to a transducer, the values
received by the hardware registers from the transducer must be recorded.
(d) Pass-fail criteria.
(1) For each test listed in §§ 3175.142 and 3175.143, the value(s) required to be calculated by the
software version under test must be compared to the value(s) calculated by BLM-approved reference
software, using the same digital input for both.
(2) The software under test may be used at an FMP only if the difference between all values calculated
by the software version under test and the reference software is less than 50 parts per million (0.005
percent) and the results of the tests required in §§ 3175.142 and 3175.143 are satisfactory to the
PMT. If the test results are satisfactory, the BLM will identify the software version tested as
acceptable for use on its website at www.blm.gov.

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§ 3175.142 Required static tests.
(a) Instantaneous flow rate. The instantaneous flow rates must meet the criteria in § 3175.141(d) for each
test identified in Table 1 to this section, using the gas compositions identified in Table 2 to this section, as
prescribed in Table 1 to this section.

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(b) Sums and averages.
(1) Fixed input values from test 2 in Table 1 to this section must be applied for a period of at least 24
hours.
(2) At the conclusion of the 24-hour period, the following hourly and daily values must meet the criteria
in § 3175.141(d):
(i)

Volume;

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(ii) Integral value;
(iii) Flow time;
(iv) Average differential pressure;
(v) Average static pressure; and
(vi) Average flowing temperature.
(c) Other tests. The following additional tests must be performed on the flow-computer software:
(1) Each parameter of the configuration log must be changed to ensure the event log properly records
the changes according to the variables listed in § 3175.104(c); and
(2) Inputs simulating a 15 percent and 150 percent over-range of the differential and static-pressure
transducer's calibrated span must be entered to verify that the over-range condition triggers an alarm
or an entry in the event log.

§ 3175.143 Required dynamic tests.
(a) Square wave test. The pressures and temperatures must be applied to the software revision under test for
at least 60 minutes as follows:
(1) Differential pressure. The differential pressure must be cycled from a low value, below the no-flow
cutoff, to a high value of approximately 80 percent of the upper calibrated limit of the differentialpressure transducer. The cycle must approximate a square wave pattern with a period of 60
seconds, and the maximum and minimum values must be the same for each cycle;
(2) Static pressure. The static pressure must be cycled between approximately 20 percent and
approximately 80 percent of the upper calibrated limit of the static-pressure transducer in a square
wave pattern identical to the cycling pattern used for the differential pressure. The maximum and
minimum values must be the same for each cycle;
(3) Temperature. The temperature must be cycled between approximately 20 °F and approximately 100
°F in a square wave pattern identical to the cycling pattern used for the differential pressure. The
maximum and minimum values must be the same for each cycle; and
(4) At the conclusion of the 1-hour period, the following hourly values must meet the criteria in §
3175.141(d):
(i)

Volume;

(ii) Integral value;
(iii) Flow time;
(iv) Average differential pressure;
(v) Average static pressure; and
(vi) Average flowing temperature.
(b) Sawtooth test. The pressures and temperatures must be applied to the software revision under test for 24
hours as follows:

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(1) Differential pressure. The differential pressure must be cycled from a low value, below the no-flow
cutoff, to a high value of approximately 80 percent of the maximum value of differential pressure for
which the flow computer is designed. The cycle must approximate a linear sawtooth pattern
between the low value and the high value and there must be 3 to 10 cycles per hour. The no-flow
period between cycles must last approximately 10 percent of the cycle period;
(2) Static pressure. The static pressure must be cycled between approximately 20 percent and
approximately 80 percent of the maximum value of static pressure for which the flow computer is
designed. The cycle must approximate a linear sawtooth pattern between the low value and the high
value and there must be 3 to 10 cycles per hour;
(3) Temperature. The temperature must be cycled between approximately 20 °F and approximately 100
°F. The cycle should approximate a linear sawtooth pattern between the low value and the high value
and there must be 3 to 10 cycles per hour; and
(4) At the conclusion of the 24-hour period, the following hourly and daily values must meet the criteria
in § 3175.141(d):
(i)

Volume;

(ii) Integral value;
(iii) Flow time;
(iv) Average differential pressure;
(v) Average static pressure; and
(vi) Average flowing temperature.
(c) Random test. The pressures and temperatures must be applied to the software revision under test for 24
hours as follows:
(1) Differential pressure. Differential-pressure random values must range from a low value, below the noflow cutoff, to a high value of approximately 80 percent of the upper calibrated limit of the
differential-pressure transducer. The no-flow period between cycles must last for approximately 10
percent of the test period;
(2) Static pressure. Static-pressure random values must range from a low value of approximately 20
percent of the upper calibrated limit of the static-pressure transducer, to a high value of
approximately 80 percent of the upper calibrated limit of the static-pressure transducer;
(3) Temperature. Temperature random values must range from approximately 20 °F to approximately
100 °F; and
(4) At the conclusion of the 24-hour period, the following hourly values must meet the criteria in §
3175.141(d):
(i)

Volume;

(ii) Integral value;
(iii) Flow time;
(iv) Average differential pressure;
(v) Average static pressure; and
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(vi) Average flowing temperature.
(d) Long-term volume accumulation test.
(1) Fixed inputs of differential pressure, static pressure, and temperature must be applied to the
software version under test to simulate a flow rate greater than 500,000 Mcf/day for a period of at
least 7 days.
(2) At the end of the 7-day test period, the accumulated volume must meet the criteria in § 3175.141(d).

§ 3175.144 Flow-computer software test reporting.
(a) The test facility performing the tests must fully document each test required by §§ 3175.141 through
3175.143. The report must indicate the results for each required test and include all data points recorded.
(b) The report must be submitted to the AO by the operator or the manufacturer. If the PMT determines all
testing was completed as required by this section, it will make a recommendation that the BLM approve
the software version and post it on the BLM's website at www.blm.gov as approved software.

§ 3175.150 Immediate assessments.
(a) Certain instances of noncompliance warrant the imposition of immediate assessments upon discovery.
Imposition of any of these assessments does not preclude other appropriate enforcement actions.
(b) The BLM will issue the assessments for the violations listed as follows:

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Appendix A to Subpart 3175 of Part 3170 - Table of Atmospheric Pressures

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