§ 1065.257 - H2O measurement devices.

§ 1065.257 H₂O 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 with a humidity generator meeting the requirements of § 1065.750(a)(6).

(b) Measurement principles. Use appropriate analytical procedures for interpretation of infrared spectra. For example, EPA Test Method 320 (see § 1065.266(b)) and ASTM D6348 (incorporated by reference, see § 1065.1010) are considered valid methods for spectral interpretation. You must use heated analyzers that maintain all surfaces that are exposed to emissions at a temperature of (110 to 202) °C.

(c) Instrument types. You may use any of the following analyzers to measure H₂O:

(1) Fourier transform infrared (FTIR) analyzer.

(2) Laser infrared analyzer. Examples of laser infrared analyzers are pulsed-mode high-resolution narrow band mid-infrared analyzers and modulated continuous wave high-resolution narrow band near or mid-infrared analyzers.

(d) Interference verification. Certain compounds can interfere with FTIR and laser infrared analyzers by causing a response similar to water. Perform interference verification for the following interference species:

(1) Perform CO₂ interference verification for FTIR analyzers using the procedures of § 1065.357. Use good engineering judgment to determine other interference species for FTIR analyzers when performing interference verification. Consider at least CO, NO, C₂H₄, and C₇H₈. Perform interference verifications using the procedures of § 1065.357, replacing occurances of CO₂ with each targeted interference species. Determine interference species under this paragraph (d)(1) that are appropriate for each H₂O infrared absorption band, or you may identify the interference species based on the instrument manufacturer's recommendations.

(2) Perform interference verification for laser infrared analyzers using the procedures of § 1065.375. Use good engineering judgment to determine interference species for laser infrared analyzers. Note that interference species are dependent on the H₂O infrared absorption band chosen by the instrument manufacturer. For each analyzer determine the H₂O infrared absorption band. Determine interference species under this paragraph (d)(2) that are appropriate for each H₂O infrared absorption band, or you may identify the interference species based on the instrument manufacturer's recommendations.

[89 FR 29795, Apr. 22, 2024]