---
kind: "section"
citation: "30 C.F.R. § 7.88"
title: "30"
number: "7.88"
heading: "Test to determine the gaseous ventilation rate."
url: "https://uscodex.org/cfr/30/7.88"
---

# §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](/cfr/30/7.89.md) 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](/cfr/30/7.86.md).
  - (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)](/cfr/30/7.87.md?p=a-3).
    - (ii) The air inlet and exhaust backpressure restrictions on the engine shall be set as specified in [§§ 7.87(a)(3)](/cfr/30/7.87.md?p=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)](#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:
    - (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:
    - (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)](#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.


## Notes

### Amendments

[61 FR 55504, Oct. 25, 1996; 62 FR 34640, June 27, 1997]

### Source

Source: 61 FR 55504, Oct. 25, 1996, unless otherwise noted.

### Authority

Authority: 30 U.S.C. 957.

### Source

Source: 53 FR 23500, June 22, 1988, unless otherwise noted.

### Amendments

[61 FR 55504, Oct. 25, 1996; 62 FR 34640, June 27, 1997]