§ 1065.266 - Fourier transform infrared analyzer.

§ 1065.266 Fourier transform infrared analyzer.

Cross Reference

Link to an amendment published at 89 FR 29796, Apr. 22, 2024.

(a) Application. For engines that run only on natural gas, you may use a Fourier transform infrared (FTIR) analyzer to measure nonmethane hydrocarbon (NMHC) and nonmethane - nonethane hydrocarbon (NMNEHC) for continuous sampling. You may use an FTIR analyzer with any gaseous-fueled engine, including dual-fuel and flexible-fuel engines, to measure CH₄ and C₂H₆, for either batch or continuous sampling (for subtraction from THC).

(b) Component requirements. We recommend that you use an FTIR analyzer that meets the specifications in Table 1 of § 1065.205.

(c) Measurement principles. Note that your FTIR-based system must meet the linearity verification in § 1065.307. Use appropriate analytical procedures for interpretation of infrared spectra. For example, EPA Test Method 320

(see https://www.epa.gov/emc/method-320-vapor-phase-organic-and-inorganic-emissions-extractive-ftir) and

in 40 CFR part 63, appendix A, and ASTM D6348 (incorporated by reference

in

, see § 1065.1010) are considered valid methods for spectral interpretation. You must use heated FTIR analyzers that maintain all surfaces that are exposed to emissions at a temperature of (110 to 202) °C.

(

c

d) Hydrocarbon species for NMHC and NMNEHC additive determination. To determine NMNEHC, measure ethene, ethyne, propane, propene, butane, formaldehyde, acetaldehyde, formic acid, and methanol. To determine NMHC, measure ethane in addition to those same hydrocarbon species. Determine NMHC and NMNEHC as described in § 1065.660(b)(4) and

§ 1065.660

(c)(3).

(

d

e)NMHC and NMNEHC

CH₄ and C₂H₆

determination from subtraction of CH₄and C₂H₆from THC. Determine

CH₄ as described in § 1065.660(d)(2) and C₂H₆ as described § 1065.660(e). Determine

NMHC from subtraction of CH₄ from THC as described in § 1065.660(b)(3) and NMNEHC from subtraction of CH₄ and C₂H₆ as described § 1065.660(c)(2). Determine CH₄ as described in § 1065.660(d)(2) and C₂H₆ as described § 1065.660(e).

(

e

f) Interference verification. Perform interference verification for FTIR analyzers using the procedures of § 1065.366. Certain

interference gases

species can interfere with FTIR analyzers by causing a response similar to the hydrocarbon species of interest. When running the interference verification for these analyzers, use interference

gases

species as follows:

(1) The interference

gases

species for CH₄ are CO₂, H₂O, and C₂H₆.

(2) The interference

gases

species for C₂H₆ are CO₂, H₂O, and CH₄.

(3) The interference

gases

species for other measured hydrocarbon species are CO₂, H₂O, CH₄, and C₂H₆.

[81 89 FR 7416329796, OctApr. 25, 2016, as amended at 86 FR 34536, June 29, 202122, 2024]