No person employed in compressed air shall be permitted to pass from the working chamber to normal air, except after decompression in a lock as follows:

1. (a) Where the air pressure is greater than normal and not more than fifteen pounds per square inch, the time of decompression shall be at least two minutes;
2. (b) Where the air pressure is more than fifteen pounds per square inch, and not more than twenty-six pounds per square inch, decompression shall be at the average rate of not more than three pounds per minute;
3. (c) Where the air pressure is more than twenty-six pounds per square inch, and not more than thirty-three pounds per square inch, decompression shall be at the average rate of not more than two pounds per minute;
4. (d) Where the air pressure is more than thirty-three pounds per square inch, decompression shall be at the average rate of not more than one pound per minute;
5. (e) Where the air pressure is more than fifteen pounds per square inch, a stage decompression shall be used in which a drop of one-half of the maximum gauge pressure shall be at the rate of five pounds per minute. The remaining decompression shall be at a uniform rate and the total time of decompression shall equal the time specified for the original maximum pressure;
6. (f) The time of decompression shall be posted in each man lock.

(from Ch. 48, par. 263)

(Source: Laws 1939, p. 614.)