Gas regulators

[karstic]

Not sure which Tech Forum to put this in so Mods move it where you best see fit. Here it goes...

Are gas (as in airgas you know O, N, CO2) regulators, gas specific? Or are they universal? I acquired three regulators that were used for oxygen, helium and I think hydrogen and was wondering if they are to be used specifically for those gases or can the be used for other types of gases, say acetylene or something else?

[ErikL]

i believe they are all the same..... damn good question

[5-90]

In general, I am inclined to say that a pressure regulator is a pressure regulator, with the main difference being the fitting meant to attach to the gas cylinder (different fittings are used to prevent getting your lines crossed.)

That being said, there are some internal differences made for safety's sake when dealing with oxidisers (oxygen gas and similar,) flammables (acetylene, propane, and similar) and corrosives (no need to go into examples here - we don't deal with any.) Also a regulator for CO2 will be different than, say, a regulator for oxygen, since the CO2 regulator has to be able to NOT fail when presented with liquid CO2 under pressure, and needs to be able to operate at low temperatures without freezing up.

So, I'd not get too happy when switching regulators back and forth - especiallly when crossing "family lines" like I mentioned above. We'd like to keep you around for a while...

5-90

[woody]

Something else to consider is that regulators for acetylene are working at very low pressures (compared to oxygen) and IIRC becomes unstable over a certain PSI... seems like IIRC one can only go up to 15 PSI. Unsure if propane has a similar upper limit.

[Matthew Currie]

That 15 psi limit for acetylene is correct. In the tank, it's dissolved in acetone so it can be pressurized more, but once it's released as a gas, you don't want it above 15. It has a nasty habit of spontaneously combusting. There's no such limit on propane. For some applications you don't even need a regulator. I could see possibly using an acetylene regulator for propane, but I'd hesitate to do the reverse.

Welding regulators have special gauges that are designed to blow out the back if they fail or if there's a flashback (thus saving the operator from a face full of gauge splinters). I'm not sure whether the ones for inert gases are the same, but you definitely don't want to use conventional gauges for welding regulators.

I wouldn't worry too much about swapping inert gases - CO2, argon, nitrogen, helium, etc., but I'd want a little more informed research before going much beyond that. You should also be aware that the adjustment range for some regulators might be unusable for other applications. I have a nitrogen regulator, for example, which I think was for telephone line use, with a range of something like 100 to 500 pounds regulated. No use for anything else. Most regulators are expected to work within a pretty narrow range, and their springs will be either too stiff or too weak to be useful out of that range.

[dmillion]

Things like CO2 and propane are stored in the tank as a liquid. The pressure in the tank is relatively low, compared to compressed oxygen and nitrogen. For that reason you should NOT use a CO2 regulator on a tank filled with compressed oxygen or nitrogen! It is NOT made to handle the high pressure!

Compressed gas regulators can can easily handle the pressure of CO2, but a CO2 regulator is made with a check valve to insure that liquid CO2 will never flow into the regulator and ruin it. A regulator made for a compressed gas will not normally have such a check valve. For that reason, you could use the compressed gas regulator, but you want to be VERY careful that you never allow liquid CO2 to get into it or you will ruin it immediately.