Dive Right In Scuba - Scuba Diving Blog

In my time working in the SCUBA industry I have fielded thousands of questions from divers who are eager to learn. One of the most regular inquiries I receive is whether or not they need an “O2 Clean” SCUBA regulator. This is a question that could be answered in a number of ways and opinions vary greatly on this subject. Before I answer the question directly, let’s first take a look at exactly what “O2 Clean” really is shall we?


What is O2 Clean?


In the simplest definition, O2 clean refers to a regulator that has been cleaned using certain approved cleaners and all sediment, contaminants, and other impurities removed from all surfaces of the regulator. In addition, special lubricants and sealing surfaces(o-rings) are used. The reason behind this is that Oxygen or O2 isn’t flammable by itself but is only a single component in the “fire triangle”. The fire triangle is Oxygen, Heat(Combustion), and Fuel.


Well, of course we have Oxygen and in the event we have a cylinder of Nitrox, or pure Oxygen…it’s more abundant than found in the atmosphere. With regards to heat, well we have high pressures and friction that can produce heat or a source of ignition. These first two components we really can’t get rid of so we make an attempt to eliminate the “fuel” portion of the triangle. Through true O2 cleaning we eliminate 3 pieces of the puzzle that can be used as fuel here. First is contaminants, the second is lubricants…by using non petroleum based products, and finally by using an alternative to rubber in sealing surfaces.


Now, here’s the tricky part to O2 clean regulators. They must remain O2 clean. If you use a true O2 clean regulator on a non O2 clean cylinder or do anything to damage the integrity of the O2 cleaning then it no longer remains to be truly O2 clean. With that in mind, how sure are you of that rental tank’s status as it pertains to O2 cleaning. To that end, to ensure a regulator’s true O2 clean status you should probably only use it on a cylinder that you own, that is filled from a source that is O2 clean, and never let someone borrow it.


What’s a Diver To Do?


Luckily, as a recreational diver you need not concern yourself with true O2 cleaning as chances are you will be diving with nitrox that maintains less than 40% of pure oxygen. Most often you won’t break 32 or 36% as those are the most common mixes. Currently in the dive industry, just about every regulator you would buy new is ready to handle mixes containing up to 40% Oxygen right out of the box. So, as a recreational diver you’re pretty much covered.


Realistically, you wouldn’t need to be concerned with true O2 clean regulators and cylinders until you enter the realm of technical diving with accelerated decompression and gasses that exceed 70% Oxygen.


Still have question or are unsure if a regulator you are looking at is able to handle gas mixes other than good ole’ air? Give the crew here at Dive Right In Scuba a shout!

One Response

  1. Aaron: one of the problems of the 40% rule is how one gets to 40%. Some folks are still using partial pressure fill method for the tanks. Using a tank that is usually filled by pre blending (mixing the oxygen and air as it enters the compressor) in a partial pressure fill method exposes the tank to pure oxygen at many times atmospheric pressure to start (usually about 600 psi in an empty tank to get in the 30%’s after the air is added to top off at 3000 psi). This can lead to a false sense of security as the “fuel” in the tank, safe at 40% is not safe during the initial pure oxygen fill. Most “oxygen clean to 40%” claims don’t really get the cylinders “oxygen” clean. Do you know if the horror stories of magnesium alloy regs igniting with high oxygen mixtures true or just stories? Thanks for your post.