SEJW: Opening valves on gas tanks...

I was taught that all tank valves except Acetylene should be opened fully to the stops. There is a new guy at the shop who knows everything, and he's sure that it only applies to oxygen tanks. In my understanding, the valves can leak slowly around the valve stem packing when partially open, but have top and bottom sealing surfaces, so that when open or closed fully, they will not leak.

Am I correct?

Thanks,

Stuart

Reply to
Stuart Wheaton
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"Stuart Wheaton" wrote: I was taught that all tank valves except Acetylene should be opened

Am I correct? ^^^^^^^^^^^^^^^^^^^^^ You are correct, except I am not sure whether it applies to CO2. It applies to the gasses that are pressurized to over 2000 psi, including oxygen, helium, argon, nitrogen. Your know-it-all is correct if his universe is limited to oxygen and acetylene.

Fuel tank valves should be opened only a turn or two, so they can be closed quickly in an emergency.

Reply to
Leo Lichtman

Does anyone have any actual data on this, I think it might be a urban legend.

This came up in a lunch discussion years ago when I was working in a large tank shop. So we soap tested all the hp cylinders in the shop and couldn't find any that leaked. I've tested others from time to time over the years, and just went out in my shop and tested 4 more after reading this post. No leaks, ever. I think it might be a myth.

Reply to
Maxwell

"Maxwell" (clip) Does anyone have any actual data on this, I think it might be a urban

^^^^^^^^^^^^^^^^^^^^ You could be right, but it is also possible that HP cylinders have excellent stem seals, plus the double seat as a backup. Most valves, like air compressor valves and faucets open wide but do not come to a firm stop in the wide open position. I believe the fact that an O2 cylinder valve reaches a firm open position when opened all the way is a clue. I don't want to try this with my acetylene, because I'm afraid if I open it too far I could get into trouble trying to close it again.

Reply to
Leo Lichtman

My thinking exactly, any valve stem that has to be able to turn must have some path for gas to slip past. When I was taught that the valve seals top and bottom, I could see the shapes needed to achieve this and why it would work, sure they must have good stem packings, but why rely on that if you can lock up tight.

The tanks in question are argon and C25.

The best solution is to see a valve out of the tank...surely somebody here works someplace where they do hydro testing....

Stuart

Reply to
Stuart Wheaton

CO2 tanks can leak around the stem if not fully opened. I had one that did, and the supplier said opening all the way was appropriate.

Reply to
Bob F

If I am doing a quick, like 5 minute, job I open O2 or He one turn.

If it's a longer job I open them all the way.

Reply to
RogerW

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