40 CFR § 1065.255 - H measurement devices.

---
identifier: "/us/cfr/t40/s1065.255"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 1065.255 - H measurement devices."
title_number: 40
title_name: "Protection of Environment"
section_number: "1065.255"
section_name: "H measurement devices."
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"
---


# 1065.255 H measurement devices.

(a) *Component requirements.* We recommend that you use an analyzer that meets the specifications in § 1065.205. Note that your system must meet the linearity verification in § 1065.307.

(b) *Instrument types.* You may use any of the following analyzers to measure H<sub>2</sub>:

(1) Magnetic sector mass spectrometer.

(2) Raman spectrometer.

(c) *Interference verification.* Certain compounds can positively interfere with magnetic sector mass spectroscopy and raman spectroscopy by causing a response similar to H<sub>2</sub>. Use good engineering judgment to determine interference species when performing interference verification. In the case of raman spectroscopy, determine interference species that are appropriate for each H<sub>2</sub> infrared absorption band, or you may identify the interference species based on the instrument manufacturer's recommendations.

[89 FR 29795, Apr. 22, 2024]