StacksVerified U.S. regulatory reference

42 CFR §84.157

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (a)The static pressure in the facepiece shall not exceed 38 mm. (1.5 inches) of water-column height.
  2. (b)The pressure in the facepiece shall not fall below atmospheric at inhalation airflows less than 115 liters (4 cubic feet) per minute.
  3. (c)The exhalation resistance to a flow of air at a rate of 85 liters (3 cubic feet) per minute shall not exceed the static pressure in the facepiece by more than 51 mm. (2 inches) of water-column height.