7.88—Test to determine the gaseous ventilation rate.
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.
(a) Test procedure.
(1)
Couple the diesel engine to the dynamometer and attach the sampling and measurement devices specified in § 7.86.
(3)
CO, CO2, NOX, and CH4 analyzers shall be zeroed and spanned at the analyzer range to be used prior to testing.
(ii)
The air inlet and exhaust backpressure restrictions on the engine shall be set as specified in §§ 7.87(a)(3) (iii) and (iv).
(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.
(iii)
A 1.0 ±0.1 percent CH4, by volume, shall be injected into the engine's intake air for category A engines.
(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.
Speed | Rated speed | Intermediate speed | Low-idle speed | |||||
---|---|---|---|---|---|---|---|---|
% Torque | 100 | 75 | 50 | 10 | 100 | 75 | 50 | 0 |
(ii)
The gaseous emission test shall be acceptable if the difference in the zero and span results taken before the test and after the test are less than 2 percent.
(i)
The following abbreviations shall apply to both category A and category B engine calculations as appropriate:
cfm—Cubic feet per min (ft3/min)
Exh—Exhaust
A—Air (lbs/hr)
H—Grains of water per lb. of dry intake air
J—Conversion factor
m—Mass flow rate (mass/hr)
TI—Intake air temperature (°F)
PCAir—Percent Air
PCCH4—Percent CH4 (intake air)
UCH4—Unburned CH4
PCECH4—Percent Exhaust CH4
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(vi)
Unburned CH4 (lbs/hr) calculation for category A engines shall be mUCH4 =(m Exh)(0.0052)(PCECH4 )
(NO wet basis)=(NO dry basis)(J)
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Where:
J=(f/a)(−1.87) (1−(0.00022)(H))
(ix)
NO and NO2 correction for humidity and temperature for category A and category B engines shall be:
(NO corr)=(NO wet basis)÷(E)
Code of Federal Regulations
Where:
E=1.0 (R)(H−75) (G)(TI−77)
R=(f/a)(0.044)−(0.0038)
G=(f/a)(−0.116) (0.0053)
(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:
(m NO)=(NO corr)(0.000470)(m Exh)
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(m CO)=(CO wet basis)(4.38)(m Exh)
(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:
(cfm NO)=(m NO)(K)
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(cfm CO)=(m CO)(K)
Where:
K=13,913.4/ (pollutant grams/mole) (pollutant dilution value specified in § 7.84(c)).
(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.
Example: 10,432 cfm shall be listed 10,500 cfm.
Example: 26,382 cfm shall be listed 27,000 cfm.