40 CFR § 1065.265 - Nonmethane cutter.

---
identifier: "/us/cfr/t40/s1065.265"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 1065.265 - Nonmethane cutter."
title_number: 40
title_name: "Protection of Environment"
section_number: "1065.265"
section_name: "Nonmethane cutter."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "U"
subchapter_name: "AIR POLLUTION CONTROLS"
part_number: "1065"
part_name: "ENGINE-TESTING PROCEDURES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
regulatory_source: "70 FR 40516, July 13, 2005, unless otherwise noted."
cfr_part: "1065"
---


# 1065.265 Nonmethane cutter.

(a) *Application.* You may use a nonmethane cutter to measure CH<sub>4</sub> with a FID analyzer. A nonmethane cutter oxidizes all nonmethane hydrocarbons to CO<sub>2</sub> and H<sub>2</sub>O. You may use a nonmethane cutter for raw or diluted exhaust for batch or continuous sampling.

(b) *System performance.* Determine nonmethane-cutter performance as described in § 1065.365 and use the results to calculate CH<sub>4</sub> or NMHC emissions in § 1065.660.

(c) *Configuration.* Configure the nonmethane cutter with a bypass line if it is needed for the verification described in § 1065.365.

(d) *Optimization.* You may optimize a nonmethane cutter to maximize the penetration of CH<sub>4</sub> and the oxidation of all other hydrocarbons. You may humidify a sample and you may dilute a sample with purified air or oxygen (O<sub>2</sub>) upstream of the nonmethane cutter to optimize its performance. You must account for any sample humidification and dilution in emission calculations.

[70 FR 40516, July 13, 2005, as amended at 73 FR 37300, June 30, 2008; 76 FR 57442, Sept. 15, 2011]