42 CFR 84.70 - Self-contained breathing apparatus; description.
(a) Limitation on scope. None of the provisions of Subpart H apply to closed-circuit escape respirators to be approved specifically for escape only from hazardous atmospheres, except as provided for under § 84.304(a)(5). Such respirators are covered under the provisions of subpart O of this part.
(b) Self-contained breathing apparatus, including all completely assembled, portable, self-contained devices designed for use as respiratory protection during entry into and escape from or escape only from hazardous atmospheres, are described as follows:
(1) Closed-circuit apparatus. An apparatus of the type in which the exhalation is rebreathed by the wearer after the carbon dioxide has been effectively removed and a suitable oxygen concentration restored from sources composed of:
(i) Compressed oxygen; or
(ii) Chemical oxygen; or
(2) Open-circuit apparatus. An apparatus of the following types from which exhalation is vented to the atmosphere and not rebreathed:
(i) Demand-type apparatus. An apparatus in which the pressure inside the facepiece in relation to the immediate environment is positive during exhalation and negative during inhalation; or
(ii) Pressure-demand-type apparatus. An apparatus in which the pressure inside the facepiece in relation to the immediate environment is positive during both inhalation and exhalation.
(1) A combination respirator which includes a self-contained breathing apparatus; and
(2) A Type “C” or Type “CE” supplied air respirator, where -
(i) The self-contained breathing apparatus is classified for 3-, 5-, or 10-minute service time and the air line supply is used during entry; or
(ii) The self-contained breathing apparatus is classified for 15 minutes or longer service time and not more than 20 percent of the rated capacity of the air supply is used during entry.