Description
A self-contained breathing apparatus (SCBA) is a device worn to provide breathable air in environments with oxygen deficiency, smoke, dangerous gases, and other airborne contaminants that may be otherwise dangerous to breathe. Workers handling hazardous materials or operating in contaminated zones are typically required to wear a self-contained breathing apparatus. Only positive-pressure SCBAs are recommended for entry into atmospheres that are immediately dangerous to life and health (IDLH).
Typically, an SCBA consists of a facemask with a hose connecting to the user’s air source. The air source can be a tank of compressed air, compressed oxygen, or an oxygen-generating chemical.
Types of Self-Contained Breathing Apparatuses
Self-contained breathing apparatuses can be broken down into escape-only or entry-and-escape modes. Escape-only SCBAs are frequently continuous-flow devices with hoods that can be donned to provide immediate emergency protection. Employers should provide and ensure that employees carry an escape SCBA where such emergency protection may be necessary.
Entry-and-escape SCBA respirators give workers untethered access to nearly all portions of the worksite but decrease worker mobility, particularly in confined areas, due to both the bulk and weight of the units. Their use is particularly advisable when dealing with unidentified and unquantified airborne contaminants.
There are two types of entry-and-escape SCBA’s: open-circuit and closed-circuit. In an open-circuit SCBA, air is exhaled directly into the ambient atmosphere. In a closed-circuit device, exhaled air is recycled by using an alkaline scrubber to remove the carbon dioxide and replenish the consumed oxygen with oxygen from a solid, liquid, or gaseous source.
