Regulations last checked for updates: May 12, 2024

Title 49 - Transportation last revised: May 09, 2024
§ 230.71 - Orifice testing of compressors.

(a) Frequency of testing. The compressor or compressors shall be tested for capacity by orifice test as often as conditions may require, but not less frequently than once every 92 service days.

(b) Orifice testing criteria. (1) Compressors in common use, as listed in the following table, shall have orifice test criteria as follows:

Make Compressor size Single strokes per minute Diameter of orifice
(in inches)
Air pressure maintained
(in pounds)
Westinghouse9 1/2120 11/6460
Westinghouse11100 3/1660
Westinghouse150 CFM 8 1/2 CC100 9/3260
Westinghouse120 CFM 8 1/2100 15/6460
New York2a120 5/3260
New York6a100 13/6460
New York5b100 15/6460

Note: This table shall be used for altitudes to and including 1,000 feet. For altitudes over 1,000 feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet increase in altitude.

(2) For compressors not listed in the table in paragraph (b)(1) of this section, the air pressure to be maintained shall be no less than 80 percent of the manufacturer's rated capacity for the compressor.

source: 64 FR 62865, Nov. 17, 1999, unless otherwise noted.
cite as: 49 CFR 230.71