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U.S. Department of Labor
Mine Safety and Health Administration
Protecting Miners' Safety and Health Since 1978 |
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30 CFR § 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 Secs. 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 ( deg. 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.
