Danger of using nitrox in non-SCUBA tanks?

[GaryBDavis]

I have an HP120 tank that I use on occasion to fill my HP air paintball tank which is actually used for a t-shirt launcher. My HP120 tank is O2 cleaned and mostly I dive it with regular air but occasionally I get a nitrox 32% fill.

I'm aware of why a cylinder has to be O2 cleaned and my LDS does partial pressure nitrox fills. 100% oxygen in the tank could explode if it comes into contact with something it's not compatible with.

I don't ever plan to use a nitox mix to fill my paintball tank but I'm curious if it posses any danger. One real possibility is that my next air fill might be slightly above 21%. I have about 700psi left in the HP120 and if I take it in for an air fill, they might not bleed it all the way down before giving it a regular air fill.

Thoughts?

 

[Superlyte27]

I fill my paintball tanks, nail guns, tires, etc with nitrox. There's no issue.

I blow the dryer vent and dryer screen with nitrox.

There's no issue.

 

[Cleavitt]

I wouldn't worry about using 32% or less in your paintball gun.

Although some might disagree on the best number, the generally accepted cutoff point is 40%. Most people treat Nitrox mixes at or below 40% the same as air (as far as oxygen compatibility). Above 40% there are special considerations.

Many dive shops do continuous blending of Nitrox as high as 40% using their compressors. In other words, 40% oxygen is fed into the compressor intake. Compressors are hot, oily, and have lots of fast moving metal parts. I would tend to think any mix that can be run through a compressor would be just fine in a paintball gun.

 

[GaryBDavis]

When I was a teenager, I mowed a lady's lawn and she provided the riding lawn mower. The tires were always flat and she filled them up with a hose and air chuck she had connected to her 500 gallon butane tank. Even as a teenager, I knew something wasn't right with that setup.

Is it standard proceedure to bleed down a nitrox fill before doing an air fill?

 

[tplyons]

Anything less than 40% oxygen is treated as air. Anything over 40% is treated as pure oxygen.

Since you'll effectively be filling with banked Nitrox, your paintball tank will not be exposed to anything greater than 40%. You'll be okay.

 

[Cleavitt]

That lady sounds like a lot of fun.

I wouldn't say that bleeding down a tank prior to an air fill is standard procedure. If the shop thinks there might be something in the tank other than air they might ask you exactly what you want. A big nitrox sticker or an experienced looking diver might prompt them to ask for example. They may always ask as a matter of policy, but I image they would get a lot of confused looks from newer divers that don't know what Nitrox is. Some customers (like myself most times) would just want the tank to be topped off with air which would result in a lean Nitrox mix.

The bottom line is it's best to tell them exactly what you want or drain the tank down yourself. If you just drop off your tanks and say something vague like "I need me some full tanks" you may get exactly that. Tanks that are full...of something...like butane.

 

[cascas]

As long as you analyse your gas before breathing it under water you'll be fine. But DO analyse !!!

Sent from my GT-N5110 using Tapatalk 2

 

[tplyons]

I wouldn't say that bleeding down a tank prior to an air fill is standard procedure. If the shop thinks there might be something in the tank other than air they might ask you exactly what you want. A big nitrox sticker or an experienced looking diver might prompt them to ask for example. They may always ask as a matter of policy, but I image they would get a lot of confused looks from newer divers that don't know what Nitrox is. Some customers (like myself most times) would just want the tank to be topped off with air which would result in a lean Nitrox mix.

This. My steel tanks have Nitrox markings and I'll most often ask for them to be topped off with air, analyze, and mark my tanks accordingly.

If I breathe down my tank to the 500 psi that my dive plans should leave me with, top off with air to 3442 psi, that'll leave me with a 22.5% mix. If I breathe THAT tank down to 500 and fill with air, I'm down to 21.2%. Yes, residual oxygen, but if I'm diving tanks that are marked for Nitrox, I'm analyzing them accordingly.

 

[rhwestfall]

One real possibility is that my next air fill might be slightly above 21%. I have about 700psi left in the HP120 and if I take it in for an air fill, they might not bleed it all the way down before giving it a regular air fill.

Around here, if you are asking for a tank of EANxx (specify mix other than 21%), the shop starts from an "empty" tank each time (and IIRC, they may pull the valve each time too). They partial pressure blend, and the charts they use have been developed based on tanks with 1 ATM and 21%, with no other option. yeah, funny, but true......

I suppose a spreadsheet could be set up to do it (or even some existing blending software), but that is how they run....

 

[GaryBDavis]

When I got the nitrox fill, they bled it down and started from zero (they do partial pressure). This will be the first time for me to take a tank in that was last used for a nitrox and ask for an air fill (I used to have dedicated tanks for air and nitrox). It's the same shop that did the nitrox fill and it's their viz/O2 clean sticker on it. We'll see what they do...