40 CFR 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 S1.4-1971
Table 1—Sound Level Corrections When Using a Type 2 (or S2A) Instrument
Measurement section | Source | Decibels 1 |
---|---|---|
201.24 | Locomotives | 0 |
Rail cars | 0 | |
Locomotive load cell test stand | 0 | |
201.26 | Retarder | 4 |
Car coupling | 2 | |
201.27 | Locomotive load cell test stand | 0 |
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.