- An SCBA is an essential piece of safety equipment in many industries.old oxygen cylinder image by cegli from Fotolia.com
Self-contained breathing apparatus (SCBA) are used in a wide range of hazardous environments including toxic atmospheres, fire and smoke and oxygen deficient areas. Because of the varying requirements of these different environments, the exact composition of a SCBA for one use may differ slightly from that for another. All configurations, however, have four basic components: the air cylinder, the backpack assembly, the regulator assembly and the facemask or facepiece. - SCBA air cylinders were made of steel in the past, but steel is no longer used because of its weight. Modern air cylinders are made of aluminum, aluminum wrapped in fiberglass or a Kevlar/carbon composite material. According to MSA Safety Co., their 1976 introduction of the fiberglass aluminum composite air tank cut the weight in half. The addition of Kevlar and carbon fibers provided an even lighter and stronger air cylinder.
High-pressure cylinders must accept pressures up to 4,500 pounds per square inch (PSI), and low-pressure cylinders between 2,216 and 3,000 psi. Each cylinder should have a rated duration, which is a predictable length of time the air in the tank will sustain its user. Rated durations are typically 30, 45 or 60 minutes. - The backpack assembly is the framework that carries the weight of the SCBA. Both the framework and the harness straps must be made of materials that will not fail in the environment where they are used, which in most cases means they are fire proof and impervious to corrosive chemicals. The straps are adjustable allowing the user to optimize the distribution of the SCBA's weight.
- As their name suggests, regulators regulate the pressure of the air delivered to the user, reducing it from the pressure in the tank to a practical pressure for delivering breathing air. Regulators can be attached to the facemask (mask-mounted) or to the belt or backpack (belt-mounted), and are available for low-pressure or high-pressure uses.
The regulator assembly also includes a low-pressure warning device, sometimes referred to as a Personal Alert Safety System (PASS) that notifies the user when air pressure drops to about 500 PSI. - The facemask must form a tight seal around the face.emergency image by Mat Hayward from Fotolia.com
The facemask or facepiece has a transparent lens made of material that can survive the hazardous environments where it is used, including heat and corrosive materials. It also must form a tight seal around the face to prevent noxious gases from entering. The facemask assembly may also include a radio communications device that includes a microphone and a speaker.
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