30 CFR § 36.49
Tests of exhaust-gas dilution system.
The performance and adequacy of the exhaust-gas dilution system shall be
determined in tests of the complete equipment. The engine, at temperature
equilibrium, shall be operated in normal air as prescribed by MSHA. Samples
of the undiluted exhaust gas and of the diluted exhaust gas, at location(s)
prescribed by MSHA, shall be considered with the data obtained from the
engine test (see §36.43) to determine that the
concentrations of carbon dioxide, carbon monoxide, oxides of nitrogen, and
aldehydes in the diluted exhaust shall be below the required concentrations
specified in §36.25(f)(1).