Blending Article 95-1

Blending Standards - A Review

By Tom Mount

As most of you are well aware, IANTD follows federal regulations.

The minimum standards are stated by OSHA, USN, NASA and NOAA. In addition, agreement was made with ANDI in a meeting at NAUI IQ in 1992 that fulfilled a directive issued following the EANx Conference pre-DEMA 1992.

This agreement was modified to include oxygen-compatible air, as defined a Tek93. We incorporated these procedures (the combined federal regulatory bodies and agreements of IANTD and ANDI) because these are the only agencies we are aware of who actually define EANx and who publish guidelines for EANx use. We do follow their gas recommendations as our minimum standard. That is, when using PREMIXED gas less than 40% it is treated the same as air. At any time pure oxygen is mixed or makes contact with any surface of the equipment it is considered as oxygen. All partial-pressure blending must incorporate Oxygen Standards.

All equipment used in partial pressure blending must be oxygen-service rated.

Per IANTD standards, equipment used in partial-pressure blending or which is in contact with oxygen or mixtures greater than 40% must be both oxygen-clean and use oxygen-compatible components. As a recommendation, IANTD encourages that each tank, even if used for air-only, to be oxygen-cleaned annually so any contaminants that may have been induced during the year will be removed. IANTD also encourages its facilities to require, as a Facility Policy, the cleaning of all cylinders used with EANx.

IANTD is not presenting an argument to any manufacturer in regard to cleaning per a given level of oxygen contained in the cylinder. IANTD is simply stating that, as a Training Agency, we endorse a policy that is accepted by federal regulatory bodies combined with the mutual agreement between IANTD and ANDI as defined in the IANTD Journal, Vol. 92-1 and in our current Standards and Procedures.

IANTD is a Training Agency and we state the agreements that have been made and referenced and our practical implementation is to require these as the minimum acceptable equipment standards.

Note! Item 4 on the second page of the Mixing Standards states that all equipment must be used in compliance with the individual manufacturer's specifications.

IANTD believes it is the right and responsibility of each manufacturer to state whether or not their equipment is suitable for use with EANx mixtures and, if not, what it takes to adapt this specific equipment for use with EANx.

It is also the manufacturer's right to state to what level of oxygen exposure the equipment is compatible.

IANTD always has, and will continue, to defer to each manufacturer in regard to use and/or modifications of their individual brands of equipment for EANx mixtures.

As a Training Agency we must advocate those minimums that are published regarding gas mixtures. These have historically been published by the federal regulatory bodies represented by the USN, OSHA and NOAA.

As a Training Agency we absolutely must, and have, deferred to each manufacturer for their requirements regarding the individual brands of equipment usage with any/all gas(es) including air.

IANTD is not a manufacturer. Our Standards simply insure that the minimum requirements, as endorsed by the above-mentioned federal bodies and the agreements entered into by ANDI and IANTD, will be complied with. IANTD Facilities are directed to comply with each manufacturer's specifications as referenced in paragraph 4 under equipment specifications in the IANTD Blending Standards. Our policy and practical implementation supports this document.

Some industry members do produce either EANx-compatible equipment or supply kits to convert them for EANx use. These are, according to at least one manufacturer, in compliance with CGA recommendations. By definition CGA describes any mixture with more than 23% oxygen as oxygen. Thus the equipment that has been rendered as EANx-compatible per CGA recommendations is presumed to be oxygen-compatible. This is an assumption that, hopefully, the manufacturers will define, as some confusion exists in the field due to the definition of air vs. oxygen by CGA..

The definitions by the USN, NOAA, OSHA and NASA as regards EANx are much clearer. This is why it is easier to provide their requirements as a minimum standard from a training agency viewpoint.

Before using any equipment for either EANx or oxygen, IANTD divers should check with their facilities who are required to communicate with the manufacturer of said equipment before putting equipment into EANx or oxygen-service. IANTD requires all equipment to be oxygen-serviceable. That is, it must be oxygen-clean and oxygen-compatible when used with any EANx mixture greater than 40% per federal standards USN MIL-SPEC-STD-777EAND MIL-SPEC STD-1330, OSHA SPEC 1910.420(I), NOAA appendix D.

IANTD recommends the detergent "Simple Green" as a cleaning agent for Nitrox equipment. This is the same detergent used by NOAA. It is effective and does not pose environmental threats, produce adverse physiological reactions in humans nor damage metals as do many solvents. Please read the letter on page 2 on the IANTD Journal Vol. 94-2, and the articles in the Vol. 94-1 on oxygen cleaning to better understand the safety issues. IANTD requires that HOT water be used in conjunction with the detergent. It is exceptionally dangerous to use "trike" (trichloroethelyne) and other toxic elements for cleaning equipment for EANx use. The liability that one faces, if using this type substance, is great. Refer to page 41 of The IANTD Blending Manual for explanations of IANTD cleaning specifications.

To summarize, IANTD as a Training Agency in compliance with federal published procedures and per mutual agreement with ANDI (see preceding statement of agreement plus the amended oxygen-compatible air as defined at Tek 93) has stated the minimums to be met from a training perspective. Individual manufacturers will define the requirements of their specific equipment and IANTD Facilities will comply with whichever of the two policies is more stringent. In this manner we are assured that proper equipment preparation, safety and liability issues are addressed by our facilities and end users.

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