View Full Version : acetylene reg. for propane?

11-29-2004, 03:32 AM
I know that its a no no to use propane reg for acet. but what about the other way around?


11-29-2004, 09:07 AM
What is the difference, a lot of shops just change torch tips.

G.A. Ewen
11-29-2004, 09:25 AM
I believe the difference is that the acetylene regulator is made to take more pressure. I used an acetylene outfit for many years with propane.
Never had an problems.

11-29-2004, 10:18 AM
LPG or propane as you call it in USA will attack the rubber O-rings and diaphram.
If you are going to use a acetelene regulator go to your welding suppliers, replace with LPG resistant O-rings & diaphram.

11-29-2004, 04:25 PM
thanks for the responses so far, what I have found on the 'net is basically what I knew already, except some guys web page that uses some sort of propane injector for making his diesel engine run "cleaner" and he uses and acet. reg. on his tank. acetelyne is dissolved in acetone, but isnt it the acetone that dissolves the rings and such?. Propane seems like it would be less of a solvent than acetone doesnt it? I just thought I would try to get the facts, but regulator mfg would like to sell me a reg for each of my tanks, one for the bbq etc etc... I am switching to oxy-lpg cutting using the reg I already have would help.


11-29-2004, 06:02 PM
<font face="Verdana, Arial" size="2">Originally posted by Samuel:
acetelyne is dissolved in acetone, but isnt it the acetone that dissolves the rings and such?. Propane seems like it would be less of a solvent than acetone doesnt it? </font>

Dangerous assumption! One of the most corrosive solvents on the earth, one that can reduce a ship into nothing, can dissolve a huge number of different materials: water.

Acetone and Propane are both solvents, but differently so. I wouldn't make the assumption that one is weaker than the other, they just react with different molecules.


11-29-2004, 11:12 PM
If you want to run propane through an acytelene regulator you will have no problems.You may need to replace the inlet and nut on the reg to fit the propane bottle.
I use my forklift bottle for my torch all the time,I just bought a forklift adapter from McMaster-Carr for $10.00,uscrewed the acy.nut and stem and threaded a 1/4npt male thread on the stem,works like a champ.

BTW,all the seals and diaphrams in the reg are Nitrile and Viton,they are impervious to anything in Propane.

11-30-2004, 09:55 AM
I have been using oxy-LPG for brazing silver solder to copper for the last 15 years and have gone through 3 sets of gauges before I knew about the incompatibilty of the gages. Since using a LPG regulator it has lasted ~8 years without maintence.

<font face="Verdana, Arial" size="2">Originally posted by wierdscience:

BTW,all the seals and diaphrams in the reg are Nitrile and Viton,they are impervious to anything in Propane.</font>

Ahh, now you reminded me to why you need to change the rubber components.
All O-rings are not inert products and will absorb oil & solvents, look at the specs of o-rings and they are specified as oil/grease RESISTANT meaning they will resist absorbing oil but nonetheless still absorb some oil swelling in the process. The same applies to solvents.
Now for a quick test.... grab one of your nitrile or vition O-rings and put in a small container of petrol(gasoline) overnight. In the morning look what happened to the o-ring, it will either have swelled or really soft.
LPG or propane & butane are all petroleum byproducts.

Second reason to why not to use viton is that it will crack under prolonged use.
Have you ever heard of propane/butane used as a refrigerant(R-600).
You will get a refrigeration effect because the regulator acts as an orrifice with high pressure at the bottle end and low pressure at the outlet end.
Viton has a working temp range of ~ -15degC to +200degC, if you have a high rate of flow as needed with LPG you have a good chance of freezing the reg and therefore exceeding the working range of viton, hardening & cracking will result.

What happens when the diaphgram ruptures is that the gas will escape through the breather hole.
If you are lucky and turn the bottles off after use you may notice the LPG purfume and fix the situation or if you are really lucky the Air/fuel ratio is too high for ignition.
If you are unlucky and don't turn bottle off after use and you arrive in the morning with that cigerette hanging out your mouth you may be helpped out the door with a blast.
LPG is heavier than air and will only dissapate with a strong air movement, ever heard of why it is not a good idea to use LPG in a boat, that watertight hull will also hold LPG down there till the right A/F ratio is reached & with an ignition source.....boom......
Offhand LPG has an A/F ratio of ~6% -11%

Do the right thing and either replace the rubber components with LPG compatable ones or buy a proper LPG reg.
Also I don't know about in the USA but here if I was found to be using a acetelene reg with LPG or vice versa work place relations would fine my arse off.
Not to mention that you had a fire, even if the reg wasn't the cause...just more fuel to the fire to as why insurance won't pay up.

Sorry about the long rant but i'm a sticklier for safety.

11-30-2004, 10:43 PM
Oz,I am only refering to regs being used on small portable rigs where the pressure is less than 18psi,beyond that a high flow propane reg must be used ,so its a non issue.

As for saftey,from having sold regs for years I can tell you that many of the mfg sell the same reg for compressed air as they do for propane,personally I would not use an air reg for propane,but they do it all the time.When the parts book specs the same repair kit for both propane and air,its a dead giveaway that its the same reg.