Argon bottle set-up question

[Buccaneer]

I recently got a good deal on a used pony bottle, and I got a spare 1st stage lying around, so I was thinking I may set this up for argon. I was at my LDS, discussing it with someone there, and Iwas told that with Argon, I had to have an over-pressure release valve on the first stage. Is this really true, and why?

 

[Peter_C]

On a standard regulator setup a 2nd stage regulator will allow the first stage to vent in case of failure (3000+ psi to everything). This means that most likely the BC inflator or a drysuit inflator valve will be able to handle the lower pressures. If an argon reg fails there is no second stage to vent pressure so an OPV, Over Pressure Valve is used.

I found the smaller argon regs are nicer since it doesn't poke into my side.

 

[it_mike]

The why of it is that if the argon tank's first stage vents due to over pressurization, there's no place for it to go except your suit. If this happens, you'll need to vent quickly or inflate like a balloon (and deal with the resultant buoyancy issue). An OPV provides a level of protection.

-- Do they teach the neck dump anymore?

 

[Buccaneer]

The why of it is that if the argon tank's first stage vents due to over pressurization, there's no place for it to go except your suit. If this happens, you'll need to vent quickly or inflate like a balloon (and deal with the resultant buoyancy issue). An OPV provides a level of protection.

-- Do they teach the neck dump anymore?

They did in my drysuit class- and I have since had to use it! One time I had my inflator valve stick when I added air and it wouldn't turn off. I did the neck dump and wasable to control my ascent, but it was freaky. I finally got it to release but it wasn't until I got to the surface. Got the thing apart on shore, and it was a tiny piece of sand/gravel that had caught in the mechanism.