40 C.F.R. § 201.22   Measurement instrumentation.

Title 40 - Protection of Environment


Title 40: Protection of Environment
PART 201—NOISE EMISSION STANDARDS FOR TRANSPORTATION EQUIPMENT; INTERSTATE RAIL CARRIERS
Subpart C—Measurement Criteria

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§ 201.22   Measurement instrumentation.

(a) A sound level meter or alternate sound level measurement system that meets, as a minimum, all the requirements of American National Standard S1.4–19711 for a Type 1 (or S1A) instrument must be used with the “fast” or “slow” meter response chacteristic as specified in Subpart B. To insure Type 1 response, the manufacturer's instructions regarding mounting or orienting of the microphone, and positioning of the observer must be observed. In the event that a Type 1 (or S1A) instrument is not available for determining non-compliance with this regulation, the measurements may be made with a Type 2 (or S2A), but with the measured levels reduced by the following amount to account for possible measurement instrument errors pertaining to specific measurements and sources:

1 American National Standards are available from the American National Standards Institute, Inc., 1430 Broadway, New York, NY 10018.

 
 Table 1_Sound Level Corrections When Using a Type 2 (or S2A) Instrument------------------------------------------------------------------------                                                                Decibels      Measurement section                   Source                 \1\------------------------------------------------------------------------201.24........................  Locomotives...................        0                                Rail cars.....................        0                                Locomotive load cell test             0                                 stand.201.26........................  Retarder......................        4                                Car coupling..................        2201.27........................  Locomotive load cell test             0                                 stand.                                Stationary locomotive.........        0------------------------------------------------------------------------\1\ Amount of correction to be subtracted from measured level (dB).

(b) A microphone windscreen and an acoustic calibrator of the coupler type must be used as recommended by: (1) the manufacturer of the sound level meter or (2) the manufacturer of the microphone. The choice of both devices must be based on ensuring that Type 1 or 2 performance, as appropriate, is maintained for frequencies below 10,000 Hz.

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