Oxygen is a highly combustible molecule. So when you have a gas mix with an oxygen concentration higher than 40%, it is imperative that your regulator, cylinder, and BC are oxygen cleaned annually.
As we also know, when you increase the pressure of a gas or substance, the heat consequentially increases also. Therefore when you have oxygen at higher pressures in a higher concentration, the chance of combustion has increased.
It is therefore particularly important to use substances which contain no hydrocarbons whilst cleaning and re-assembling components of a SCUBA system, unless the system is only going to be used for compressed air. .
When servicing a regulator, tank valve, SPG or BCD; it is important that the parts are cleaned in a hydrocarbon free solution, any possible contaminants introduced in the previous year will be removed and re-assembled with care as to not introduce any new contaminants or hydrocarbons. Even things such as nylon seats in tank valves must be replaced with parts which are oxygen compatible.
One of the most vital things which we use when re-assembling SCUBA systems is the lubricant. As silicon contains hydrocarbons (which are not suitable for compatibility with Oxygen Enriched mixtures), we use a lubricant called Christo-Lube® MCG 111. It is Oxygen compatible, can be used with common rubbers (including the oxygen compatible o-rings used) and polymers and has a wide compatible temperature range. It has even been tested by NASA with oxygen mixtures up to 690 bar. Christo-Lube® MCG 111 is also chemically inert, meaning that it is chemically inactive.
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