§ 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.
( 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. ( i ) The parameter for fa shall be calculated in accordance with § 7.87(a)(3).
( ii ) The air inlet and exhaust backpressure restrictions on the engine shall be set as specified in §§ 7.87(a)(3) (iii) and (iv).
( 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. Table E-2—Gaseous Test Modes
Speed
Rated speed
Intermediate speed
Low-idle speed % Torque
100
75
50
10
100
75
50
0
( 8 ) After completion of the test modes, the following shall be done: ( i ) Zero and span the analyzers at the ranges used during the test.
( 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.
( 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: 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
( 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: PCAir = 100−PCCH4 Y = (PCAir)(0.289) + (PCCH4)(0.16) Z = (0.16)(PCCH4) ÷ Y mCH4 = (A)(Z) ÷ (1−Z)
( 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: (NO wet basis) = (NO dry basis)(J) (NO2 wet basis) = (NO2 dry basis)(J) (CO2 wet basis) = (CO2 dry basis)(J) (CO wet basis) = (CO dry basis)(10−4)(J) 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) (NO2 corr) = (NO2 wet basis) ÷ (E) 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) (m NO2) = (NO2 corr)(0.000720)(m Exh) (m CO2) = (CO2 wet basis)(6.89)(m Exh) (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) (cfm NO2) = (m NO2)(K) (cfm CO2) = (m CO2)(K) (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. ( 1 ) Ventilation rates less than 20,000 cfm shall be rounded up to the next 500 cfm. Example: 10,432 cfm shall be listed 10,500 cfm.
( 2 ) Ventilation rates greater than 20,000 cfm shall be rounded up to the next 1,000 cfm.
Example: 26,382 cfm shall be listed 27,000 cfm. [61 FR 55504, Oct. 25, 1996; 62 FR 34640, June 27, 1997]