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Class A Air??

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.


New Member
Jan 15, 2005
I recently joined a Volunteer dive team and I noticed that they are using the Fire Department compressor for air fills. The compressor is rated for class E air. Is this satisfactory??? They have been doing this for quite some time and I do not believe they have ever had any problems. Most of our cases are in shallow (less than 20ft) water. Can this air be used for recreational diving? Any thoughts......... :confused:
This is a Crib but I think it covers what you need.

What is Class E air? Compressed air is sampled and tested quarterly for purity. Air falls into different levels of purity called Class. Class D is commonly used for SCBA or fire department use under normal ambient pressure. It has up to 1000 ppm carbon dioxide. Class E is suitable for scuba diving with up to 500 ppm* of CO2, but with up to 25 ppm of hydrocarbons. Class J has up to 500 ppm of CO2 and less than .1 ppm hydrocarbons suitable for oxygen applications.

If a tank or regulator was O2 cleaned and O2 compatible, care must be taken to use only Class J air or there is risk of contamination.

* CGA (Compressed Gas Association) has raised the CO2 standard for class E to 1000 ppm.


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