Do not do this. Regulators for propane and acetylene have springs and diaphragms designed for completely different inlet and outlet gas pressures and are not interchangeable, whether threads will fit or not and regardless of gauge pressures.

You could cause a dangerous high pressure release of flammable gas which could be a major fire risk if you use wrong regulator on wrong gas.

I suggest you ask your local gas supplier for correct regulators for use on their cylinders.

Please don't risk your safety for a few pounds' worth of gas regulating equipment.

Acetylene cylinder is at about 190 psi at 50 degrees F while Propane is at about 320 psi at about the same temperature. You can see that the Acetylene regulator is working at quite a bit lower pressure with acetylene so it seems likely its regulator is not going to take kindly to 320 psi up its chuff with the possible associated uncontrolled release of all that nasty flammable gas !!!

ME TOO. Maybe 55+ years altogether. I believe my regulators have metal diaphragms.

Me too. In fact I've just been using it… Mine too has been on a 18kg bottle for 25 years and it still ain't empty…or leaking .

Hi, I strongly recommend that you do not use any regulator that has not been designed for the gas you are using whether it has been used for 40 odd years or not. All regulators are designed with materials that are suited to the gas that is being used with it, it is not just the pressures you have to concern yourself with. It may well be that you have been using one for 40 or more years without any trouble, but one knock can case a failure you do not want to be near. Regulators have only a guarantee of five years by the manufacturer and this is its life period even if it hasn't been used. One thing you need to think about is, what are the legal consequences if there is a failure and someone was seriously injured or killed. You may not be subject to HSE at work, but you could find that your insurance will not pay out and or be in a court of law if someone is injured or killed by using equipment not designed for it's purpose. Remember fuel gasses are explosive, so please don't get complacent about them.

All fuel gas regulators have a left hand thread for the pipes and connection to their respective cylinder.

Regards Nick.

And don't run with scissors!

Or use a propane torch near a naked flame

Propane regulators have a service pressure of 25 bar!

IIRC from my school days, acetylene has a bad habit of polymerising in to benzene with a vast release of energy from it's triple carbon bond. To keep it safe they dissolve it in acetone and the acetone is soaked into a something spongy, a bit like soaking nitroglycerine in to kieselguhr. If the tank gets warm of it's own accord you place it gently in the nearest ditch and stand well back. I spent a lot of my childhood throwing calcium carbide down holes in the ground followed by "water" and a match.

That is the sum total of my knowledge of acetylene, what gauge you use is beyond me

A major concern when following "used it for decades with no problems" advice with modern components is that modern equipment tends to be much more specifically engineered than "good old stuff". Its frequently safe to assume that the lower end, economy range components will have given up and been dumped years ago so survivors tend to be of good quality. Production issues back in the old days may well have meant minimum changes to a standard design to cover a range of gases and applications was better than trying to make regulators specifically designed for each application. If this is the case the old design will be able to handle worst case, highest pressures, so the only issue will be whether the adjustment range gives sufficient controllability when fitted with springs for a different application.

More modern equipment is almost certainly engineered for its specific application so going outside what was intended is probably risky. Especially as the likes of us will probably be purchasing economy range components which perform well enough when doing what they were designed to do but don't have the safety margins to handle a different job. Economy gear is intended too be bought, used and thrown away after what might be considered a relatively short life so the engineering is appropriate for that.

Clive.

Hi Nick

Difference between should be and are.

I know for an absolute fact that the high pressure regulators on the white-spot nitrogen bottles I used at RARDE / DERA / DRA / QinetiQ were not changed in 20 years. Not new when I took the lab on and still there when I left. Pretty sure that the regulators on the welding bottles in the section workshop and those on the various gases the chemists used went lots longer than five years too. Not sufficiently intimately involved to be certain but pretty sure I'd have heard if they were. I do know of hoses being changed due to developing leaks from age but regulators left untouched!

Government (MoD) research establishment with theoretically hot safety department generating reams of paper , procedures and multiple inspections. All trivial and total waste of my time. Flag up anything serious and "no budget to fix" followed by "just get on and do the job from line management".

Research use is bit different from factory being mostly occasional short bursts rather than all the time so presumably an easier life for regulators.

Clive.