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Alternative Measurement Protocols for Biogas and Renewable Natural Gas

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The Renewable Fuel Standard regulations require that biogas and renewable natural gas used to produce renewable fuels must be measured using methods specified in the regulations under 40 CFR 80.155(a)(1) or (2) or using an EPA-approved alternative measurement protocol (AMP) under 40 CFR 80.155(a)(3). The table below lists AMPs approved by the EPA and the requirements for use.

To use an EPA-approved AMP, interested biogas and RNG producers must submit the information described under 40 CFR 80.135(c) or (d), as applicable, as part of their registration submissions. Producers must specify the AMP flowmeter type and submit all of the following related information1:

(A) A description of why they are unable to use meters that comply with the requirements specified in § 80.155(a)(1) and (2), as applicable.

(B) A description of how measurement is conducted including any applicable standards with the measurement description (e.g., see table below).

(C) Any standards or specifications that apply (see table below).

(D) A description of all routine maintenance and the frequency that such maintenance will be conducted.

(E) A description of the frequency of all measurements and how often such measurements will be recorded under the AMP.

(F) A comparison between the accuracy, precision, and reliability of the AMP and the requirements specified in § 80.155(a)(1) and (2), as applicable, including any supporting data including the applicable standards with accuracy, precision, and reliability specifications (e.g., see table below).

The table below replaces the previous table of approved Alternative Measurement Protocols for Biogas and Renewable Natural Gas which listed EPA determination letters by company. If you are a company with an approved EPA determination, it is still in effect (refer to the archived version of this page). EPA does not plan to issue company-specific determination letters going forward. For each flowmeter type, all corresponding standards and requirements must be met.

EPA-Approved AMPs under 40 CFR 80.155(a)(3)
Flowmeter Type All Applicable Standards and Requirements by Flowmeter Type
Orifice plate
  • ISO 5167-2 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 2: Orifice Plates
  • API MPMS 14.3 – Orifice Metering of Natural Gas
  • ASME MFC 3M Measurement of Fluid Flow in Pipes Using Orifice, Nozzle, and Venturi
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Cone meter
  • ISO 5167-5 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 5: Cone meters
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Venturi
  • ISO 5167-4:2022 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 4: Venturi tubes
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Thermal dispersion
  • ASME MFC-21.2-2010, Measurement of Fluid Flow by Means of Thermal Dispersion
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Thermal mass
  • EN 17526 Thermal-mass flow-meter based gas meter
  • ISO 14511 Measurement of fluid flow in closed conduits — Thermal mass flowmeters
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Rotary
  • ANSI B109.3 ROTARY-TYPE GAS DISPLACEMENT METERS
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Coriolis
  • AGA Report No. 11 (API MPMS Chapter 14.9) Measurement of Natural Gas by Coriolis Meter
  • ASME MFC-11 Measurement of Fluid Flow by Means of Coriolis Mass Flowmeters
  • ISO 10790 Measurement of fluid flow in closed conduits – Guidance to the selection, installation, and use of Coriolis flowmeters (mass flow, density, and volume flow measurements)
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Vortex flowmeter
  • API MPMS Chapter 14 – Natural Gas Fluid Measurement Section 12 – Measurement of Gas by Vortex Meters 
  • API MPMS Chapter 14 – Natural Gas Fluids Measurement Section 1 – Collecting and Handling of Natural Gas Samples for Custody Transfer
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.
Ultrasonic
  • ISO 17089-2 Measurement of Gas by Multipath Ultrasonic Meters
  • ASME MFC-5.1 Measurement of Liquid Flow in Closed Conduits Using Transit-Time Ultrasonic Flowmeters
  • ISO 17089-1 Measurement of fluid flow in closed conduits – Ultrasonic meters for gas, Part 1: Meters for custody transfer and allocation measurement
  • Additional calibration requirements:
    • General requirements for the competence of testing and calibration must be performed according to OIML R137 Parts 1 and 2 at a competent calibration laboratory (e.g., ISO/IEC 17025 and ANSI Z540).
    • If the flow meter is calibrated with a fluid other than RNG, the equivalency to RNG flow must be demonstrated.

Note 1: See 40 CFR Part 80 Subpart E 80.135(c)(3)(iii) or 40 CFR Part 80 Subpart E 80.135(d)(3)(iii), as applicable.

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Last updated on April 16, 2025
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