Supplied air respirator (SAR) systems, also referred to as airline respirators, provide safe breathable air from a cylinder or compressor in low-oxygen environments or where air quality is compromised. Wearers are connected to an air source outside the immediate work area and their mobility is limited to the length of the airline. Air filtration products, such as air purification panels, manifolds, and filters, help ensure Grade D breathable air is available through SAR systems.

SAR systems are typically used in extremely hazardous work environments or in workplaces that have unknown fumes or risks. Common applications include abrasive blasting and grinding, spray painting, industrial cleaning, arc welding, and work performed in confined spaces.

SAR systems are approved for conditions where the use of air-purifying respirators is precluded:

• In the presence of substances that would generate a high heat reaction with the adsorbent in an air-purifying respirator.
• Where chemicals in the atmosphere are adsorbed very poorly by the adsorbents used in air-purifying respirators or where the chemicals are not adsorbed at all.
• Where two or more contaminants are present—such as ammonia and mercury—for which different air-purifying elements are recommended, and a combination element is not available.
• When the concentration of a substance is greater than the approved limit, i.e., the assigned protection factor (APF) times the permissible limit (PEL) for an air-purifying respirator.

SAR system assemblies are lightweight and designed for long-, continuous work periods. They include loose-fitting hoods, helmets, full-facepiece masks, or half-facepiece masks. Complete systems include a supplied airline hose, air regulating valve, breathing tube, and facepiece of choice.

SAR systems are defined as constant-flow or pressure-demand respirators. Constant-flow (CF) respirators, sometimes referred to as continuous-flow, deliver an uninterrupted supply of clean, fresh air that is inhaled and exhaled back into the system. Pressure-demand (PD) respirators deliver a constant stream of air to the wearer and are used in hazardous conditions. They supply air only when the pressure in the wearer's mask decreases, as the wearer inhales. PD respirators preserve air but allow more inward leakage, as such they can only be used with a sealed elastomeric mask, not a loose-fitting hood or helmet.

In the event of an emergency where an air-supply line is compromised, SAR system users can utilize a backup air tank or escape cylinder. These devices allow workers enough time to escape the dangerous area. Emergency escape breathing apparatus  are independent from this section and should be selected based on the working environment and surrounding hazards.

Atmosphere-supplying respirator parts and accessories support and maintain the function of atmosphere-supplied respirators including SAR systems and air compressors.

Regulatory compliance details can be obtained at the individual product level.