42 C.F.R. § 84.87 Compressed gas filters; minimum requirements.
Title 42 - Public Health
All self-contained breathing apparatus using compressed gas shall have a filter downstream of the gas source to effectively remove particles from the gas stream.
Title 42: Public Health
PART 84—APPROVAL OF RESPIRATORY PROTECTIVE DEVICES
Subpart H—Self-Contained Breathing Apparatus
§ 84.87 Compressed gas filters; minimum requirements.

