Do I Need Medical-Grade Oxygen

By Francois Burman, Pr Eng, MSc

DAN introduced the first standardized emergency oxygen course for divers as lay providers in 1991. More people trained in oxygen delivery means that providers in dive locations worldwide need to have emergency oxygen units available Obtaining oxygen refills, however, is an ongoing problem, because procuring medical-grade oxygen requires a prescription.

Oxygen has other dive-related uses Technical and rebreather divers require enriched-gas mixtures up to pure oxygen and often use partial-pressure techniques to make nitrox, heliox, and trimix In some applications, most commonly for commercial divers, surface decompression occurs in a hyperbaric chamber, with the divers breathing pure oxygen to complete their decompression obligation These applications are not medical, but they require pure, breathing-gas-quality oxygen.

What is pure oxygen, what is breathing oxygen, and how can you obtain oxygen for nonmedical use? The South African Bureau of Standards (SABS) in its standard SANS 532-2009 (a new revision is due later this year), provides a specification for oxygen and classifies oxygen in gas form into four grades: medical oxygen, aviation and industrial grades (99 5% pure), and food grade (99 0%) Aviation grade needs to meet the highest specifications of all grades but is also the most expensive due to the analytical requirements.

Medical oxygen should only be dispensed by a medical prescription; there is no restriction on aviation grade.

The same process produces almost all pure oxygen gas, and the primary differences are simply the requirements for analysis certificates An acceptable, safe and available alternative to medical oxygen is aviation grade oxygen , which is perfectly acceptable for all breathing-oxygen applications, but medical applications administered by or under the supervision of a physician require compliance with the SANS 532 medical oxygen standard.

Some industry gas supply companies will be unwilling to fill your cylinders and offer only the option of renting theirs. While it might seem financially motivated, they might believe they can control their equipment’s cleanliness and might doubt the cleanliness of yours. Compressing oxygen is not without its dangers, some of which are related to contamination inside the cylinder and valve.

Purely from a statutory point of view, only aviation oxygen can be used to fill breathing oxygen cylinders, and not the other way around You will need to do your own shopping for prices and availability, but aviation oxygen is the highest quality oxygen for dive-related activities, including technical mixes, emergency oxygen by the layperson, and rebreather cylinder refills.

Oxygen is oxygen, and if the purity exceeds 99 percent, it is safe for use where pure oxygen is required The critical consideration is if you need breathing gas, in which case only medical and aviation grades meet our (South African) requirements.