Understanding Nitrox Ready and Oxygen Service

Can I use it with Oxygen? Yes and no; this simple question has a complex answer because there is no widely recognized scuba diving standard for what constitutes suitability for oxygen service. Hypothetically, the equipment we sell could be used with oxygen if we describe it as "Nitrox Ready", otherwise you should assume air only (less than 23.5% oxygen) service. However from the point of view of stringent U.S. aerospace guidelines and Compressed Gas Association handling standards for oxygen, nothing in general use in recreational diving is suitable for oxygen service.

According to our suppliers, their Nitrox Ready products are oxygen compatible and oxygen clean from the factory for use with compressed gases greater than 23.5% oxygen. Nonetheless, the 'clean state' of the equipment applies only prior to initial use. Thereafter, periodic inspection and cleaning are a necessity. In terms of cleanliness and compatibility with oxygen, there is no difference between "Nitrox Ready" and "Oxygen Service" prior to initial use.

Almost all suppliers in the recreational dive industry, in an effort to reduce the risks associated with oxygen-related fires and explosions, specify their products for use with gas mixtures containing less than 100% oxygen. The maximum value of 40% Enriched Air Nitrox (EAN 40) is widely referenced in the dive industry as Nitrox Ready. To better understand the issues, please read our companion article About '40% MAX OXYGEN' Disclaimers.

However, compressed gas handling experts in most other U.S. industries do not recognize the limits referenced by the dive industry for oxygen content; expert opinion considers equipment and handling as either suitable for use with pure oxygen or only suitable for use with air, there is no in-between. The Compressed Gas Association does not have a definition for 'Nitrox Ready', 'Suitable for Enriched Air Service', 'Cleaned for Premix Oxygen Content to 40%' or similar phrases. The CGA has recently clarified in their standards that equipment and systems handling any gas in excess of 23.5% oxygen by volume shall be designed, cleaned and prepared as if the gas was pure oxygen.

Oxygen-related fires and explosions can result in serious injury or death. Ultimately, you must make the final decision to assume all risks associated with the use of any compressed gases, including those in excess of 23.5% oxygen.

Although controversial, some dive industry professionals are of the opinion that Nitrox Ready products do not have to be dedicated to oxygen service and may be used interchangeably with CGA Grade "E" air as long as the Nitrox Ready product never contacts gas mixtures in excess of 40% oxygen. However, handling best practice includes a recommendation that equipment and systems handling gases containing more than 23.5% oxygen should always be dedicated exclusively to oxygen service.

Recently we've noticed a few dive retailers are describing some of their SCUBA products as "Nitrox Ready up to 23.5%". There is no standardized definition of Nitrox Ready, but we interpret that unusual statement as saying the product is only suitable for use with Air. (The CGA defines Air as containing from 19% to 23.5% oxygen.) We think that has the potential to be very misleading if the product is not oxygen compatible or not oxygen clean.

You must meticulously follow the recommendations of the Department of Transportation (DOT), Compressed Gas Association (CGA), and other federal/state/local regulations, plus your dive training agency for equipment maintenance, handling, storage, labeling, filling, transport and use of compressed gases containing oxygen. The Compressed Gas Association describes in their pamphlet CGA P-1 "Safe Handling of Compressed Gases", the guidelines for proper handling of compressed gases containing oxygen. The pamphlet CGA G4.1 "Cleaning Equipment for Oxygen Service", describes the methods for inspecting and cleaning equipment used in the production, storage, distribution and use of oxygen.

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