TRAINING
Oxygen Safety and Gas Mixing for Dive Operations: Handle with Care – by Joel Silverstein, www.joelsilverstein.com
Joel is an industry leader and a Technical Diving Instructor Trainer (TDI) who has authored nitrox and mixed gas training materials for organizations such as NAUI, YMCA, and NOAA. Since 1990, he has mixed and analyzed diving gases and manufactured thousands of nitrox analyzers through his company, Tech Diving Limited. As an expe- rienced expedition leader and contributor to the NOAA Diving Manual, Joel is dedicated to improving diving safety and professional standards
Nitrox is the standard breathing gas at many dive resorts, with most produc- ing it on-site through membrane sepa- ration or partial pressure blending. While these methods provide cost sav- ings and a reliable gas supply, they pose significant hazards, especially when
Membrane Systems: Lower Risk, Still Needs Over- sight: Membrane systems reduce the need to handle pure oxygen directly by using gas separation technology to create nitrox, removing nitrogen from compressed air. The resulting gas typically contains around 32% oxygen and is sent to stor- age banks or gas boosters at high pressure. Although membrane systems reduce some hazards, they require regular maintenance. Neglecting the filters can lead to contamination from hydrocarbons or moisture, which may decrease oxygen output, damage the system, or introduce hy- drocarbons into the entire system. “Air to mix with oxygen is an oil contamination issue.” Glenn Butler, Life Support Technologies Cleanliness is Life: Oxygen Service Standards: Oxygen supports combustion. Contaminants like oil, silicone, and de-
working with oxygen or nitrox mixtures containing over 23.5% oxygen. Safe operation requires strict adherence to oxygen handling procedures and system maintenance, as complacency can lead to serious consequences. This article outlines the operational and safety requirements for nitrox production, based on industry standards, NFPA guidelines, and urges dive professionals to protect their staff, clients, and facilities by ensuring proper respect for oxygen and its delivery systems. Partial Pressure
bris in an oxygen (O ₂ ) system can act as fuel, so all components must be cleaned to oxygen serv- ice standards. The cleaning process involves degreasing with compatible solutions, ul- trasonic agitation to re- move contaminants, and thorough rinsing. Clean- liness testing using pH
Mixing: High Risk, High Responsibility: Partial pressure blending is a common method for producing nitrox, in- volving the introduction of pure oxygen into a scuba cylinder, which is then filled with hydro- carbon-free air. While
cost-effective and straightforward, this method poses signif- icant hazards due to the handling of pure oxygen at pressures exceeding 2,000 psi. Filling errors and rapid pressurization can lead to fires or explosions, particularly from adiabatic compression, where quick oxygen flow can cause heat spikes over 1,300°F, potentially igniting metal. To minimize these risks, dive centers must ensure: All oxygen-contact components are properly cleaned ▪ and rated for O ₂ service. Oxygen fill rates are limited to 50–100 psi per minute. ▪ Staff are trained to open valves slowly and avoid filling ▪ closed systems.
strips and blacklight inspection follows. Components are then dried with pure nitrogen or filtered air, reassembled with halocarbon lubricants, and handled with gloves to prevent recontamination. The term “clean for oxygen service” is valid only on the day of cleaning; any subsequent contamination makes the components unsuitable for oxygen mixing. For example, fill- ing a cleaned cylinder with air from a non-oxygen-maintained station can lead to contamination. In the industry, the "40% Rule" suggests that equipment not exposed to more than 40% oxygen does not need clean-
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