Supplied-Air 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. Half mask inlets can protect against up to 500 micrograms of lead per cubic meter of air. Full facepiece inlets can protect against up to 2,500 micrograms of lead per cubic meter of air.

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. Loose-fitting facepieces are effective for up to 1,250 micrograms of lead per cubic meter of air. Hoods and helmets can sometimes be effective for up to 50,000 micrograms of lead per cubic meter of air, but must be individually tested and proven to provide this level of protection. If they do not meet this test, they are considered to be as effective as a loose-fitting facepiece.

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. These SARs are available with half mask inlets, which provide protection up to 2,500 micrograms of lead per cubic meter of air, or full facepiece inlets, which are effective for up to 50,000 micrograms of lead per cubic meter of air. SARs with full facepiece inlets are sufficient to protect workers doing level 3 trigger tasks, such as abrasive blasting or welding.

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 Construction Lead Exposure visit our Cal/OSHA Construction Lead Exposure Online Training web page.