Figure 2-12. Gas mask.
(2) General limitations. No protection is provided against particulate
contaminants, unless specified on canister or cartridge label. A rise in canister or
cartridge temperature indicates that a gas or vapor is being removed from the inspired
air. This is not a reliable indicator of canister performance. An uncomfortably high
temperature indicates a high concentration of gas or vapor and signals a potentially very
hazardous environment, which requires a different form of respiratory protection.
(3) Gas masks. Gas masks include all completely assembled air
purifying masks that are designed for use as respiratory protection during entry into
atmospheres not immediately dangerous to life or health or escape only from
hazardous atmospheres. Gas masks are further described according to the types of
gases or vapors they remove. They may be front mounted and back mounted
(consisting of a full face piece, a canister which is usually attached to the face piece,
and associated connections).
(b) Limitations. Gas masks shall be used only for escape from (not
entry into) immediately dangerous to life or health (IDLH) atmospheres and shall not be
used against gases or vapors with poor warning properties or which generate high
heats or reaction with solvent materials in the canister. In addition, eye protection may
be required when escape type gas masks are used. In general, gas masks have only