Acetylene regulator / propane

[RRMBKParticipant @rrmbk]

[RRMBKParticipant @rrmbk]

Hi All.

Is there any reason that an acetylene regulator cannot be used on a propane cylinder,? the threads and the pressure range is the same. I know about the difference in hose specification but I already have proper propane hoses.

I was wondering really whether it is worth keeping the Acetylene reg as a spare for the propane torch.

[MWParticipant @mw27036]

I would imagine that the gauge suitability is relative to the size of the cylinder, and therefore specific to it's pressure.

Generally speaking, I would've thought it would be okay so long as you know its suitably rated with regards to the pressure.

Michael W

[Jeff DaymanParticipant @jeffdayman43397]

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.

[Brian Sweeting 2Participant @briansweeting2]

Acetylene bottles have left hand threads I'm not sure about propane but would recommend checking.

[NigeParticipant @nige81730]

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 !!!

[mark costello 1Participant @markcostello1]

My propane cylinder develops 100 psi at rest. I have used a propane cylinder with an Acetylene regulator since way before I found out the caution when the Internet came along. It's been used that way for almost 40 years. Does not seem much of a worry now.

[John ReeseParticipant @johnreese12848]

Posted by mark costello 1 on 16/11/2017 15:49:59:

I have used a propane cylinder with an Acetylene regulator since way before I found out the caution when the Internet came along. It's been used that way for almost 40 years. Does not seem much of a worry now.

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

[NigeParticipant @nige81730]

I guess experience will beat theory most of the time

[HacksawParticipant @hacksaw]

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 .

[SillyOldDufferModerator @sillyoldduffer]

As an acetylene regulator is designed not to exceed 8 to 10 psi on the output side it will produce less heat than a Propane regulator. Obviously if you don't need the extra heat then the lower output of an acetylene regulator doesn't matter.

Connecting up the other way round is seriously dangerous though: never put a Propane regulator on an acetylene cylinder. It could ruin your day by exploding.

Dave

[Nicholas FarrParticipant @nicholasfarr14254]

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.

[vintagengineerParticipant @vintagengineer]

**LINK**

[Nick HulmeParticipant @nickhulme30114]

And don't run with scissors!

[nigel jones 5Participant @nigeljones5]

Or kiss wasps

[HacksawParticipant @hacksaw]

Or use a propane torch near a naked flame

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Nige on 16/11/2017 15:44:26:

Acetylene cylinder is at about 190 psi at 50 degrees F while Propane is at about 320 psi at about the same temperature.

I think you'll find that is for 50 C. You are very unlikely to be working with your propane cylinder that hot in the U.K.

Russell

[vintagengineerParticipant @vintagengineer]

Propane regulators have a service pressure of 25 bar!

[not done it yetParticipant @notdoneityet]

Propane is at about 320 psi at about the same temperature.

I would rather believe engineering toolbox dot com, which shows about 10Bar at 300K.

Using the correct regulator is a simple enough principle to follow – for safety reasons alone.

[RobinParticipant @robin]

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

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Robin on 17/11/2017 14:59:10:

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

Hi Robin, I don't know how warm you are taking about, but if it reaches a significantly higher temperature than its ambient temperature, you must not move it at all. In the days gone by, the advice was to move it outside and cool it by putting it into a tank of water or by hosing it down with water. This advice was discontinued at least 15 years ago, maybe even 20, the reason being that it can be detonated by the slightest knock when it is in this state. This was discovered during a fire, when a fireman was moving a hot cylinder by churning it along the floor, but it then came to a small step of less than 50mm and as the cylinder rolled down it, it exploded and of course, killed the fireman. If you ever have a concern about an Acetylene cylinder getting hot, get everybody away from the immediate area and call the fire brigade pronto. Acetylene is the most explosive gas there is, however a Propane explosion will expand too five times its volume. (That's the volume of gas, not the size of the cylinder)

Regards Nick.

[Clive FosterParticipant @clivefoster55965]

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.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Clive, all regulators and flashback arrestors for that matter, should be replaced after five years from manufacture, this has always been the case that I've known since I've done my City & Guilds back in the beginning of the 70's and this includes those that have never been out of the box. This is in line with the British Compressed Gasses Association's codes of practice, and this is what any court case would be judged by, should any incidents arise. Whether anyone follows the BCGA codes of practice or not is there own concern, as it is not a legal requirement to do so. Yes there are regulators that can be used for more than one gas, but they will be marked accordingly and will be a higher price no doubt.

Regards Nick.

[Clive FosterParticipant @clivefoster55965]

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.

[the artfull-codgerParticipant @theartfull-codger]

I've also use an acetylene regulator on my propane bottle for the last 40 odd yrs with no adverse effects, & as for changing them at 5 yrs well all I can say if you feel the need to, go ahead but I certainly won't change mine & I've never had a problem in all those years,the odd soapy water test now & again doesn't go amiss, I've been using mine today with my flamefast brazing hearth, it only uses about 2-3psi propane, flamefast wanted about £30 to "convert" my guns to propane as they were natural gas, I wasn't paying that so I just tried it on propane as they were & they work fine, the only difference is the gas regulation is very sensitive.

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