SCBAs

SCBAs, or self-contained breathing apparatuses, are portable respirators that provide breathable air from a cylinder carried by the user. They are designed for use in environments where the surrounding air is unsafe due to smoke, toxic gases, oxygen deficiency, or extreme particulates, allowing the wearer to work for a limited time under hazardous conditions.

Most SCBAs used in firefighting and industry are open-circuit units. They supply air from high-pressure cylinders through a regulator to a facepiece or hood, with the user breathing the air directly from the cylinder as needed. A typical system includes a cylinder, a pressure regulator, a pressure gauge, a facepiece, a harness, and sometimes a built-in warning device or PASS unit. Cylinder sizes and breathing rates determine the duration of use, commonly ranging from about 15 to 60 minutes.

There are also specialized configurations and variants, including closed-circuit or semi-closed rebreather systems used in limited contexts, but open-circuit SCBAs remain the standard in most emergency and industrial settings. Industry standards and regulatory guidance for SCBAs exist in multiple regions, with notable examples such as NFPA 1981 for SCBA units and NFPA 1982 for personal alert safety systems in the United States, and EN 137 in Europe.

Maintenance and use involve regular pre-use checks, leak testing, and periodic servicing of regulators and hoses. Cylinders undergo hydrostatic testing at prescribed intervals, and components such as batteries and elastomer seals are inspected and replaced as needed. SCBAs have finite air supply and considerable weight, which can impact mobility and heat management; they are unsuitable in oxygen-deficient atmospheres where the air is not breathable.