View all text of Subpart H [§ 84.70 - § 84.104]
§ 84.77 - Inhalation and exhalation valves; minimum requirements.
(a) Inhalation and exhalation valves shall be provided where necessary and protected against damage and distortion.
(b) Exhalation valves shall be—
(1) Protected against external influence; and
(2) Designed and constructed to prevent inward leakage of contaminated air.