Used Alum 80s filled with Nitrox

[ktgould]

I purchased two used Alum 80s - hydros good till 2013. Unfortunately they are filled with Nitrox (newbie here, so I can't use). is there anything special that needs to be done berfore filling them with air, short of emptying them?

 

[deepstops]

Empty and refill, you're good to go

 

[ktgould]

Empty and refill, you're good to go

Thanks! Couldn't beat the price ($80.00 for both)!

 

[redacted]

Or you could determine what the mix is, give yourself a crash course in MOD for nitrox (Maximum operating depth - Wikipedia, the free encyclopedia) and dive them using air tables or computer.

 

[GrumpyOldGuy]

If you are not going to be using nitrox, peel off the ugly green labels when you empty the tanks and only bleed them down to 100psi to avoid a visual.

If you leave the labels on, you always have the potential for someone to fill it with nitrox without you knowing it. Since you dive air, you are not analyzing it and you would never realize what happened. Could be a problem if you then dive deep.

 

[ktgould]

If you are not going to be using nitrox, peel off the ugly green labels when you empty the tanks and only bleed them down to 100psi to avoid a visual.

If you leave the labels on, you always have the potential for someone to fill it with nitrox without you knowing it. Since you dive air, you are not analyzing it and you would never realize what happened. Could be a problem if you then dive deep.

FANTASTIC advice! THANK YOU!

 

[Peter Guy]

Query -- why would someone fill the tanks with "Nitrox" unless a mix was specified? What shop would just do "a fill" without knowing what was wanted?

 

[H2Andy]

Peter, i hear you

but many shops have a Nitrox "standard" (i.e. 32) which they bank and use unless otherwise specified

unlikely to happen, true ... but you never know

 

[halocline]

Do you know what mix is in them? It's very easy to find out the MOD (maximum depth you can dive with that mix) once you know the O2 percentage. If I were in your position, I'd find that out and just dive with them, AS LONG AS you don't go anywhere near the MOD, and AS LONG AS the mix is under 40%. No reason to waste a good $20 worth of nitrox. Do you have a computer? If so, and you know the mix, you can set your computer to that mix and dive away, or if not, just dive on air tables. If you are well short of the MOD and calculate N2 loading just like normal on air, you'll be fine. Once you've used up this fill, then remove the sticker and fill with air.

There are only a few really serious safety considerations with using these tanks as is. One, don't exceed the MOD( for the third time), and make sure you know what the MOD is at 1.4pp for that blend. (There are lots of places to find out that info) Two, there is a maximum allowable O2 exposure for a given 24 hr period, but if you only have 2 dives' worth, you won't go anywhere near that. Three, you must really know what the mix is, and that means having someone analyze them. If you have a buddy that's nitrox certified and can dive with him/her, all the better. Truthfully there is no great mystery or skill associated with using nitrox, the main things are to know what the blend is (with confidence) and do not dive too deep for that blend. It's really that simple in this case. (2 tanks already filled and analyzed) Extended nitrox use, planning dives for a particular blend (or blend for a particular dive), dealing with accumulated O2 exposure, etc, those are the sorts of things covered in the course.

I can already hear the flamethrowers warming up, so I would also advise you to: 1) take this as a sign and just take a nitrox course, then use the tanks, and 2) If you are not comfortable in any way with using them while not nitrox certified, don't.

 

[deepstops]

No reason to waste a good $20 worth of nitrox. Do you have a computer? If so, and you know the mix, you can set your computer to that mix and dive away, or if not, just dive on air tables. If you are well short of the MOD and calculate N2 loading just like normal on air, you'll be fine. Once you've used up this fill, then remove the sticker and fill with air.

Matt,

While I agree diving nitrox isn't rocket science, you're a DM advocating "learning to dive nitrox on the internet" :shocked2: