--- kind: "section" citation: "40 C.F.R. § 80.155" title: "40" number: "80.155" heading: "Sampling, testing, and measurement." url: "https://uscodex.org/cfr/40/80.155" --- # §80.155. Sampling, testing, and measurement. - (a) **Continuous measurement—** - (1) **Biogas, treated biogas, and RNG measurement.** Except as specified in [paragraph (a)(3)](#a-3) of this section, any party required to measure the volume of biogas, treated biogas, or RNG under this subpart must continuously measure using meters as specified in paragraphs [(a)(1)(i)](#a-1-i) and [(ii)](#a-1-ii) of this section or have an accepted alternative measurement protocol as specified in [paragraph (a)(2)](#a-2) of this section. - (i) In-line GC meters compliant with ASTM D7164 (incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)), including sections [9.2](/cfr/40/9.2.md), [9.3](/cfr/40/9.3.md), [9.4](/cfr/40/9.4.md), [9.5](/cfr/40/9.5.md), [9.7](/cfr/40/9.7.md), [9.8](/cfr/40/9.8.md), and [9.11](/cfr/40/9.11.md) of ASTM D7164. - (ii) **Flowmeters compliant with one of the following—** - (2) **Alternative measurement protocols.** EPA may accept an alternative measurement protocol if the party demonstrates that the alternative measurement protocol is at least as accurate and precise as the methods specified in [paragraph (a)(1)](#a-1) of this section. An alternative measurement protocol may include less frequent measurement or recording than specified in the definition of continuous measurement. - (3) **RNG RIN separator measurement.** An RNG RIN separator must measure natural gas or renewable CNG/LNG using one of the following: - (i) **A method specified in paragraph (a)(1) or (2) of this section.** - (ii) Documentation (e.g., pipeline or utility statements, scale tickets, or bills of lading) that establishes the volume of natural gas or renewable CNG/LNG. Documentation must be specified in Btu LHV or converted as specified in [paragraph (f)](#f) of this section. - (b) **Biogas and RNG sampling and testing.** Any party required to sample and test biogas or RNG under this subpart must do so as follows: - (1) Collect representative samples of biogas or RNG using API MPMS 14.1 (incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (2) **Perform all the following measurements on each representative sample—** - (i) Methane, carbon dioxide, nitrogen, and oxygen using EPA Method 3C (see appendix A-2 to [40 CFR part 60](/cfr/40/part60.md)), ASTM D1945, ASTM D1946, or ASTM D7833 (all incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (ii) Hydrogen sulfide and total sulfur using ASTM D5504, ASTM D6228, or ASTM D6968 (all incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (iii) Siloxanes using ASTM D8230 (incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (iv) Moisture using ASTM D1142, ASTM D4888, ASTM D5454, or ASTM D7904 (all incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (v) Hydrocarbon analysis using EPA Method 18 (see appendix A-6 to [40 CFR part 60](/cfr/40/part60.md)), ASTM D1945, ASTM D1946, ASTM D7833, or EPA Method TO-15 (all incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (vi) Heating value and relative density using ASTM D3588 (incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (vii) If the RNG producer blends non-renewable components into RNG, carbon-14 analysis using ASTM D6866 (incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (3) EPA may approve a party's request to use a method other than those specified in [paragraph (b)(2)](#b-2) of this section if the party demonstrates one of the following: - (i) The alternative analysis provides information that is reasonably accurate to that determined by the applicable method specified in [paragraph (b)(2)](#b-2) of this section. - (ii) The alternative analysis is required by pipeline specifications or has been approved to be used by a State or Federal government agency. - (c) **Digester feedstock.** Any party required to test for total solids and volatile solids of a digester feedstock under this subpart must do so as follows: - (1) Samples must be tested in accordance with Part G of SM 2540 (incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (2) Samples must be obtained, stored, and tested in accordance with Part A of SM 2540, including Sections [2](/cfr/40/2.md), [3](/cfr/40/3.md), and [5](/cfr/40/5.md) (Sources of Error and Variability, Sample Handling and Preservation, and Quality Control). - (3) Parties must test each daily representative sample under paragraphs [(c)(1)](#c-1) and [(2)](#c-2) of this section unless the party has a composite sampling plan submitted to EPA under [§ 80.135(c)(10)(vi)(D)](/cfr/40/80.135.md?p=c-10-vi-D). Parties with a composite sampling plan must either test each daily representative sample or test samples in accordance with Part A of SM 2540 and as specified in the facility's composite sampling plan. - (d) **Digester operations.** Any biogas producer required to measure or calculate digester operating conditions under this subpart must determine digester operating conditions for each mixed digester that meet all the following requirements: - (1) Digester temperature readings must be recorded no less frequent than every 30 minutes and represent the average temperature in the tank. - (2) Digester hydraulic and solids mean residence times must be calculated no less frequent than once a day using measurements of inflows, outflows, and tank levels, as applicable. - (3) Other parameters must be measured and calculated as specified in the facility's registration under [§ 80.135(c)(10)(vi)(A)(4)](/cfr/40/80.135.md?p=c-10-vi-A-4). - (e) **Third parties.** Samples required to be obtained under this subpart may be collected and analyzed by third parties. - (f) **Unit conversions.** - (1) A party converting between Btu HHV and Btu LHV for biogas, treated biogas, natural gas, or CNG/LNG must use the ratio of HHV and LHV of methane as specified in ASTM D3588 (incorporated by reference, see [§ 80.12](/cfr/40/80.12.md)). - (2) A party with documentation under [paragraph (a)(3)](#a-3) of this section that is not specified in Btu must convert to Btu LHV as follows: - (i) A party converting between scf and Btu LHV for CNG must use 934 Btu LHV/scf. - (ii) A party converting between pounds and Btu LHV for LNG must use 21,240 Btu LHV/lb. - (g) **Liquid measurement and standardization.** Any substance that is liquid at STP must be measured in gallons and standardized according to [§ 80.1426(f)(8)](/cfr/40/80.1426.md?p=f-8). ## Notes ### Amendments [88 FR 44564, July 12, 2023, as amended at 90 FR 29759, July 7, 2025; 91 FR 16486, Apr. 1, 2026] ### Source Source: 88 FR 44564, July 12, 2023, unless otherwise noted. ### Authority Authority: 42 U.S.C. 7414, 7521, 7542, 7545, and 7601(a). ### Source Source: 38 FR 1255, Jan. 10, 1973, unless otherwise noted. ### Amendments [88 FR 44564, July 12, 2023, as amended at 90 FR 29759, July 7, 2025; 91 FR 16486, Apr. 1, 2026]