Supplied Air Respirators
Supplied air respirators (SAR) are used in situations where air purifying respirators (APR) cannot give the wearer sufficient protection from airborne concentrations of a chemical (or a combination of chemicals) and dangerous gasses or vapors. These respirators (sometimes referred to as airline respirators) are also utilized where unknown chemicals may be present, in oxygen deficient atmospheres, in Immediately Dangerous to Life and Health (IDLH) situations or when chemicals that absorb poorly in chemical cartridges for APR's are present.
The OSHA Respiratory Standard 29 CFR 1910.134 covers regulations for air purifying and supplied air respirators. The determination of the type of respirator to use is made by conducting a workplace or work site assessment. That requirement can be found in the Standard 29CFR 1910.134(d)(1)(iii). Once an assessment has been completed and engineering controls have been ruled out, a SAR selection process can begin. The SAR and equipment used in respiratory protection must be NIOSH approved.
Airline systems deliver air to a variety of face pieces, the type being used depends on the situation and the best fit for the job at hand. There are tight fitting full-face and half-mask respirators, loose fitting hoods, helmets and self-contained breathing apparatus (SCBA). Airline respirators operate in one of two modes: continuous flow (CF) or pressure demand (PD). Continuous flow gives the user a steady flow of air and pressure demand releases air to the user when they breathe in and there is a pressure differential.
Tight Fitting Full-face and Half-mask Respirators — These respirators are used in situations where the Immediately Dangerous to Life and Health (IDLH) is met or exceeded and when gases and vapors are present that APR’s cannot protect against. Fit testing is required when using a negative or positive pressure tight fitting mask. (CFR 1910.134(f))
Loose Fitting Hoods — Hoods can be either disposable or reusable. Typically these hoods are made of Tyvek®, coated TyvekQC® or polyethylene or polypropylene type material. Hoods are used in many situations. They are used where there are cleaning chemicals and there is a chance of splash or contamination or where a cartridge type respirator would have ineffective sorbents for the chemicals being used. They are also used in auto body and painting applications where they can protect from dust and overspray. Healthcare, pharmaceutical, food and beverage and manufacturing are other industries that also use these types of systems. Loose Fitting Hoods do not require fit testing.
Air Supplied Helmets — These are typically used in grinding, sanding, painting and if approved for it, blasting applications. Helmets provide top impact and penetration protection and also protect the wearer from abrasive rebound and airborne contaminants. These are considered loose fitting and fit testing is not required.
Self-Contained Breathing Apparatus (SCBA) — SCBA’s are used in Immediately Dangerous to Life and Health (IDLH) situations or where the concentrations of chemicals or substances are unknown. The public typically sees these used by firefighters and those that respond to hazardous material situations. In industry SCBA’s are used or kept for emergency purposes. The masks for these also can be Pressure Demand or Continuous Flow. The tanks can have different pressures and be 30 minute or 60 minute air capacity. Typical is 2216 psi (Low Pressure) or 4500 psi (High Pressure). High pressure is used in strenuous activities where more air is needed. The advantage to these systems is that they offer full mobility without being attached to an airline.
Grade D breathing air can be delivered in several forms. It can come from an air compressor or plant air, which can be filtered and regulated. Per OSHA 29 CFR 1910.134(i)(1)(ii), compressed air must meet the requirements of the Compressed Gas Association (CGA) specifications of Grade D breathing air. The CGA requirements specify oxygen content and contaminant limits.
Portable ambient air pumps which deliver filtered low pressure air can be used when compressed air is not available. Air pumps transfer air from a clean air environment to the contaminated area. Air cylinders, also called bottled air, contain high pressure air and are used in confined spaces or areas where portable air is needed.
Airline SARs are available as high pressure or low pressure systems. A high pressure SAR is the best option when a long airline is required (up to 300 feet), or if the air supplying the mask needs to be heated or cooled. However, the air source for a high pressure SAR may not provide Grade D air without using an air filtration system and monitoring the carbon monoxide level. A low pressure SAR uses a portable ambient air pump, in which air is pumped from a clean source or compressor that provides Grade D air. The airline length of a low pressure SAR with an ambient air pump is generally limited to 100 to 150 feet (depending on the ambient air pump manufacturer recommendations) and supports only a few workers. There are also fewer options to heat and cool the air supplying the mask with a low pressure SAR.
Quick Connect Couplings — The example to the left is of two 1/4” Schrader quick connect couplers. These can come in either steel or brass. Quick connect couplings consist of a male plug and a female coupling; different coupling designs connect in different ways. One of the most common quick connect configurations involves female connectors with sliding or retractable sheaths which lock the male and female ends together.
The brand of quick connect couplers, also referred to as fittings, used on airlines can vary by manufacturer. Different brands of respirators use different brands of fittings for their hoses and connection points. Some of the more common fittings used are: OBAC, Hansen, Schrader and Industrial Interchange. The fittings also come in different sizes such as 3/8”, 1/4” and 1/2”. The fittings must be of the same brand and size to connect together and work properly.
Several agencies are responsible for researching and establishing contaminant exposure limit levels for hazardous substances. The American Conference of Governmental Industrial Hygienists (ACGIH) is a voluntary organization of safety professionals that develops and reviews exposure limit values. ACGIH results are based on animal, human and industrial studies. The National Institute for Occupational Safety and Health (NIOSH) is a federal agency that conducts research on safety and health concerns. NIOSH is responsible for developing and revising recommended exposure limits for hazardous substances. The recommendations are then conveyed to the Occupational Safety and Health Administration (OSHA), a federal agency in the Department of Labor which has safety, regulatory and enforcement authority over most industry and business.
Commonly Asked Questions
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The content in this newsletter is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific compliance questions should refer to the cited regulation or consult with an attorney.
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