Nitrox conversion

[Zebra mussel]

Hello. Is it necessary to install a nitrox conversion kit for a Sherwood Blizzard regulator that is approx. 8 years old. What exactly needs to be done?. Is it needed for all percentages of nitrox?. Im considering getting a nitrox cert and heard that not all regulators are nitrox compatible. Any input would be very helpful as Im fairly uninformed on this subject. Thanks in advace.

 

[DA Aquamaster]

In general for any regulator first stage the o-rings will need to be replaced with nitrox compatible o-rings and the interior surfaces should be O2 cleaned to remove any oil or petroleum based silicone grease residue. The o-rings and appropriate reg parts are then lubricated with an O2 compatible lubricant like Christolube. The full treatment like this will normally allow use of the first stage with anything up to and including 100% O2.

It is more commonly stated now that an off the shelf reg can be used with nitrox mixes up to 40% but then most manufactuers now use O2 compatible o-rings and lube as a general practice. With a really old reg that may not have been serviced recently or where the static o-rings may be the original ones that came with the reg, taking it into a shop and asking them to make it nitrox compatible when completing the annual service is a good idea.

Titanium first stages are not recommended for nitrox use as are some ultralight aluminum first stages. The old stand by chrome plated brass is the preferred material for a nitrox or O2 reg.

A fire in the first stage is the big threat with nitrox and this usually just involves a brief flash fire when the reg is turned on where the o-rings get crispy fried and then leak profusely. The idea of O2 cleaning is to remove the petroleum based silicone lubricants and o-rings that provide fuel for the fire.

The biggest risk is when the tank valve is first turned on by rapidly cranking the tank valve open and instantly putting full IP into the IP spaces and compression chamber of the first stage. This can develop a good deal of heat and this heat then becomes a potential ignition source. Turning it on slowly and having the purge button on the second stage depressed will go a long way to preventing any problems even in a non nitrox clean reg. Basically you are removing the ignition source even though the fuel may still be there.