30 CFR §7.88
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
The test shall be performed in the order listed in Table E-2. The test for determination of the particulate index described in § 7.89 may be done simultaneously with this test.
Example: 10,432 cfm shall be listed 10,500 cfm.
Example: 26,382 cfm shall be listed 27,000 cfm.
- (a)Test procedure.
- (1)Couple the diesel engine to the dynamometer and attach the sampling and measurement devices specified in § 7.86.
- (2)A minimum time of 10 minutes is required for each test mode.
- (3)CO, CO2, NOX, and CH4 analyzers shall be zeroed and spanned at the analyzer range to be used prior to testing.
- (4)Run the engine.
- (5)The engine shall be at a steady-state condition before starting the test modes.
- (i)The output from the gas analyzers shall be measured and recorded with exhaust gas flowing through the analyzers a minimum of the last three (3) minutes of each mode.
- (ii)To evaluate the gaseous emissions, the last 60 seconds of each mode shall be averaged.
- (iii)A 1.0 ±0.1 percent CH4, by volume, shall be injected into the engine's intake air for category A engines.
- (iv)The engine speed and torque shall be measured and recorded at each test mode.
- (v)The data required for use in the gaseous ventilation calculations specified in paragraph (a)(9) of this section shall be measured and recorded at each test mode.
- (6)Operate the engine at each rated speed and horsepower rating requested by the applicant according to Table E-2 in order to measure the raw exhaust gas concentration, dry basis, of CO, CO2, NO, and NO2, and CH4- exhaust (category A engines only).
- (i)Test speeds shall be maintained within ±1 percent of rated speed or ±3 RPM, which ever is greater, except for low idle which shall be within the tolerances established by the manufacturer.
- (ii)The specified torque shall be held so that the average over the period during which the measurements are taken is within ±2 percent of the maximum torque at the test speed.
- (7)The concentration of CH4 in the intake air shall be measured for category A engines.
- (8)After completion of the test modes, the following shall be done:
- (9)The gaseous ventilation rate for each exhaust gas contaminant shall be calculated as follows—
- (i)The following abbreviations shall apply to both category A and category B engine calculations as appropriate:
- (ii)Exhaust gas flow calculation for category B engines shall be (m Exh) = (A) + (m fuel).
- (iii)Fuel/air ratio for category B engines shall be (f/a) = (m fuel) / (A).
- (iv)Methane flow through category A engines shall be determined by the following:
- (v)Exhaust gas flow calculation for category A engines shall be (m Exh) = (A) + (m fuel) + (m CH4)
- (vi)Unburned CH4 (lbs/hr) calculation for category A engines shall be mUCH4 = (m Exh)(0.0052)(PCECH4)
- (vii)Fuel/air ratio for category A engines shall be (f/a) = ((m fuel) + (m CH4)−(m UCH4)) ÷ (A)
- (viii)Conversion from dry to wet basis for both category A and category B engines shall be:
- (ix)NO and NO2 correction for humidity and temperature for category A and category B engines shall be:
- (x)The calculations to determine the m of each exhaust gas contaminant in grams per hour at each test point shall be as follows for category A and category B engines:
- (xi)The calculations to determine the ventilation rate for each exhaust gas contaminant at each test point shall be as follows for category A and category B engines:
- (b)The gaseous ventilation rate for each requested rated speed and horsepower shall be the highest ventilation rate calculated in paragraph (a)(9)(xi) of this section.