Figure 2─l4. Air-line respirator (A) and self-contained respirator (B).
c. Self-Contained Breathing Apparatus
(1) Description. The self-contained breathing apparatus (SCBA) includes all
completely assembled, portable, self-contained devices designed for use as respiratory
protection during entry into and escape from or escape only from hazardous
(a) Open circuit apparatus. An apparatus from which exhalation is
vented to the atmosphere and not re-breathed. This may be demand type apparatus (in
which the pressure inside the face piece in relation to the immediate environment is
positive during exhalation and negative during inhalation), or it may be pressure
demand type apparatus (in which the pressure inside the face piece in relation to the
immediate environment is positive during both inhalation and exhalation).
(b) 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
compressed, chemical, liquid oxygen, or an oxygen generation solid.
(a) General. Use is permissible in IDLH atmospheres. The period
over which the device will provide protection is limited by the amount of air or oxygen in