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Testing compressed breathing air and compressor alarms

Summary A refinishing-products company asked how OSHA interpreted compressor alarms and breathing-air quality checks. OSHA said an oil-lubricated compressor alarm had to be audible, that testing frequency depended on the system and use, and that a suitable measuring instrument could verify air quality. It also said oxygen content had to be checked against the applicable breathing-air specification.
Document
Federal opinion letter
Agency
Occupational Safety and Health Administration (OSHA)
Document number
1994-04-25-1
Date issued
April 25, 1994
Status
Active
Status last verified October 9, 2026
Topics
Workplace Safety OSHA 1910 Respiratory Protection Breathing Air
Source
View the official document

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About this page: The full text below is the official document from Occupational Safety and Health Administration (OSHA). Ezel adds the plain-English summary and tracks the document's status. The official source linked on this page is authoritative for any reliance.

April 25, 1994

Mr. Robert Verb
DeVilbiss Automotive Refinishing Products
[Recipient address omitted]
Dear Mr. Verb:

Your letter of January 11, addressed to Mr. Roger Clark, former Director of the Compliance Programs Directorate of the Occupational Safety and Health Administration (OSHA) concerning the quality of compressed breathing air has been referred to the Directorate of Technical Support for response.

You requested that OSHA provide you with clarifications for the definition of an "alarm", the testing frequency of a supplied air source, the acceptability of a chemical indicator as a measuring instrument for air quality, and whether the oxygen content of breathing air should be verified.

An "alarm" is an audible device which is installed on the oil lubricated air compressor. A length of stain changing chemical gas detector tube is not considered an "alarm".

Since the breathing air system and the frequency of use vary among different users, there is no single testing frequency of air quality which will be satisfactory for all users. When a new breathing air system is installed, the air quality should be tested more frequently to establish a baseline for changing the air purification agents. Once the baseline is established, the testing frequency can be adjusted according to the service life of the air purification agents.

OSHA does not require the use of a specific instrument to verify the compliance of air quality requirements prescribed in the Compressed Gas Association Commodity Specification for Air, CGA G-7.1. Any measuring instrument which has an accuracy of ± 25% at a 95% confidence limit is acceptable.

Since the OSHA respiratory protection standard, 29 CFR 1910.134, requires that the breathing air must meet the specifications prescribed in the CGA G-7.1, and since the oxygen content in the breathing air is a requirement of the CGA G-7.1, it is imperative that oxygen content be verified in the air source.

Please feel free to contact Ching Bien at (202) 219-7065 if you have any questions.

Sincerely,

Stephen J. Mallinger
Acting Director
Directorate of Technical Support

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