Determine remaining welding gas in cylinder

[yomax4]

You can mooch off that tank down to 10 CFH and lower in a controlled atmosphere until you start to get porosity. I get my gas Free and I still do it

 

[Todd727]

Without any fancy formulas, if you started out at 3000 psi at room temperature, and it now reads 200 psi at room temperature, you now have 1/15th the gas. 1/15th of 330 is 22 cubic feet.

Actually, your formula is spot on. It's really that easy and just a simple ratio. However, I believe his 330 cu. ft. cylinder is 2400 psi when full. The OP will have to verify, but he can plug the numbers in. Anyway, 330/2400 = x/200. Cross multiply and you get 2400x=330*200. Solve for x=(330*200)/2400=27.5 cu ft. This assumes a constant temperature for the gas.

 

[Tractorguy24]

Thanks for all of your replies! If I remember right, they actually charge the cylinders to 3000/3500 psi but have a limitator of some sort in the cylinder valve which limits the exiting gas to 2400/2500 psi.

 

[ultrarunner]

Depends on what the cylinder is rated for... some are allowed a percentage over rating.

 

[yomax4]

Depends on what the cylinder is rated for... some are allowed a percentage over rating.

Correct. They usually pump in a couple hundred extra psi in the tanks.

 

[BeezFun]

Is it possible to determine how much c25 gas I have left in my 330 cu ft.cylinder? Is there a formula or some rule of thumb? It is at 200psi right now.
Thanks!

Some places won't take a tank back for refill if there isn't enough pressure left to crack the valve and blow out contaminants.

 

[ultrarunner]

^^^ Or charge a purge fee.

 

[yomax4]

News to me. Purge fee? Not surprised but i remember they purged all cylls with nitrogen prior to filling. That was a while back. I always found it strange that back then I guess we had an Ozone issue and they said it was from Greenhouse gasses or CO2. So the Gov was cracking down on CO2 use (prices went Up) but the Gov also mandated that all CO2 tanks had to be blown down and purged prior to fill. There were always a dozen or more CO2's blowing down at any given time.

 

[Tractorguy24]

You can mooch off that tank down to 10 CFH and lower in a controlled atmosphere until you start to get porosity. I get my gas Free and I still do it

How do you get it for free?

 

[ultrarunner]

I give away gas with each cylinder... the Hospital Manifold for Nitrogen switches at 155 lbs to maintain 150 psi system wide... so the cylinders still have 150 psi each when they go back...

Same with Oxygen except the switch is at 55 psi to maintain 50 psi...