Title 42
SECTION 84.77
84.77 Inhalation and exhalation valves; minimum requirements.
§ 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.