How Do You Add To The First Stage?

[Rick Murchison]

I attached a new inflator hose to my LP port and I didn't lubricate the O ring because I wasn't sure if my silicone grease was a potential fire hazard when using nitrox. I'm assuming it wasn't because I only use nitrox within recreational limits, it was the LP port so the partial pressures of o2 aren't that high and the supplied O ring wasn't a nitrox O ring, but I thought this thread was a good opportunity to check...

I guess in a long-winded way I'm asking if regular silicone grease is nitrox compatable.

...and what is the deal with the green O rings you get in nitrox tanks? What are they made of, and if the O rings are a potential source of fuel why are regular O rings ok on the hoses?

Sorry if this is a bit of a hijack but I thought it was important

ns

Lots of back-to-back questions here...
Some green o-rings are oxygen compatible, some are no more than cosmetic, so color alone is no indicator of anything. (I think one company provides *all* their o-rings in green)
Unless you're using your regulator for high oxygen content decompression mixes then "regular" o-rings are fine. Most folks agree that the 40% rule applies (for silicone grease, too).
Be aware that there are exceptions... I think ANDI still insists on oxygen compatibility for Nitrox, as does the US Navy, and silicone grease is not oxygen compatible.
Rick

 

[noobascooba]

Well, you should know this from your nitrox class, so it may be a good idea to go back and review the book. But, to answer your question, silicone is not 02 compatible. However, regulators do not contact more than 40% in recreational nitrox, so it doesnt matter. Green ORings can be made of anything, but depending on the manufacturer are probably viton, which has a higher combustion temperature, iirc. Just dont think that if its green its automatically compatible. O Ring makers can make them any color.

That's what I thought (apart from about the viton, I'd forgotten that). I assumed the tank valve O ring was an issue because it may experience higher PO2 if it's filled by partial pressure filling. I could be wrong, but I think I've only seen the green O rings on O2 cleaned tanks.

Sorry if it was a dumb question but there is a lot of stuff in my agencies' training materials that is a little ambiguous, and I'd rather ask questions and get second opinions than carry on in ignorance/ curiosity.

 

[MSilvia]

It's good to know what greases/lubricants are not O2 compatable, but it's perhaps easier to remember a popular one that is, and assume others are not unless they specificly say so.

I use christolube for my oxygen clean lubrication needs.

 

[GLENFWB]

In spite of what some may tell you (your LDS included, most likely), it's not rocket science and you can easily do this yourself.

First of all,

Thanks for the great information, I appreciate everyones help.