There are three basic classes of supplied air-line respirators listed here:
- Continuous flow - has a regulated amount of air fed to the facepiece and is normally
used where there is an ample air supply such as that provided by an air compressor
- Demand flow - delivers air flow only during inhalation and requires a suitable pressure
regulator to make sure that the air is reduced to the proper pressure for breathing. Such
respirators are normally used when the air supply is restricted to high-pressure
compressed air cylinders
- Pressure-demand flow - provides a positive pressure during both inhalation and
exhalation. This may be the best choice for conditions where the possible inward leakage
(caused by the negative pressure during inhalation in demand systems) is unacceptable and
the relatively high air consumption of the continuous-flow units is unacceptable.
Types A, B, and C that are approved for abrasive blasting
are designated AE, BE, and CE respectively. These respirators are equipped with additional
devices designed to protect the wearer's head and neck against impact and abrasion from
rebounding abrasive material and with shielding to protect the windows of facepieces,
hoods, and helmets. |
