Supplied Air Purifying Respirators

Supplied air respirators (SARs) provide breathable air from a tank or air compressor connected by a hose, rather than filtering air in from the environment. Supplied air respirators operate in three different modes: demand, continuous flow, and pressure-demand.

In demand mode, the regulator admits air into the facepiece only when the user inhales, similar to a non-powered APR. Demand mode SARs are only available with tight-fitting inlets, since they require a tight seal in order to recognize a change in pressure.

Continuous flow mode supplies air at a constant rate, rather than only during inhalation or exhalation. This mode provides the same protection as pressure demand mode, but also works with loose-fitting facepieces, hoods, or helmets.

Pressure demand mode works similarly to PAPRs. The respirator constantly creates positive pressure inside the mask, keeping the admission valve open until the user exhales. This makes breathing easier and provides greater protection.

SARs can offer a lot of protection since they do not rely on outside air. The disadvantages are decreased mobility and the possibility of the supply hose closing off or getting disconnected.

To learn more about Cotton Dust Safety visit our Cal/OSHA Cotton Dust Safety Online Training web page.