StacksVerified U.S. regulatory reference

42 CFR §84.77

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (a)Inhalation and exhalation valves shall be provided where necessary and protected against damage and distortion.
  2. (b)Exhalation valves shall be—
    1. (1)Protected against external influence; and
    2. (2)Designed and constructed to prevent inward leakage of contaminated air.