40 CFR 89.304 - Equipment required for gaseous emissions; overview.
(b) The exhaust is tested for gaseous emissions using a raw gas sampling system as described in § 89.412 or a constant volume sampling (CVS) system as described in § 89.419. Both systems require analyzers (see paragraph (c) of this section) specific to the pollutant being measured.
(c) Analyzers used are a non-dispersive infrared (NDIR) absorption type for carbon monoxide and carbon dioxide analysis; a heated flame ionization (HFID) type for hydrocarbon analysis; and a chemiluminescent detector (CLD) or heated chemiluminescent detector (HCLD) for oxides of nitrogen analysis. Sections 89.309 through 89.324 set forth a full description of analyzer requirements and specifications.