What PSI are propane tanks rated for?

[ZmOz]

I was bored today so I turned my old air conditioner into an air compressor. I'm surprised how well it works, about 1 CFM in near silence. Since the compressor is capable of 300+ PSI I want to attach it to an air tank I can pump that high. What is the maximum PSI rating on a 20# propane tank? I tried google but couldn't find anything. What is the pressure releif valve normally set at?


Where's bondo when you need him?

 

[Xcusme]

Re: What PSI are propane tanks rated for?

Here's an interesting read.....
http://www.propanecouncil.org/files/10202_Battelle_Cylinder_Report_Final.pdf

 

[Bob_VT]

Re: What PSI are propane tanks rated for?

A few things... old propane tanks are cheap..... plentiful and cheaply made.

Before you charge one with air be advised it can turn into a bomb. YOU MUST Purge the tank (I use nitrogen) to make sure all the propane is gone. A small amount of propane will explode is placed in a high pressure (air) tank.

 

[SS MAYFLOAT]

Re: What PSI are propane tanks rated for?

A/C compressors will work for awhile, but in due time without oil circulating thru them, they will end up failing. Is it a tin can unit, semi hermetic, or is it the old style that has to be turned by a seperate motor? The old style is more likely to last using it as an air compressor since they have a crankcase with oil.

For safety sake, get one of those cheap air storage tanks. They are already set up with a relief valve, shutoff, and usually a pressure guage. Propane tank as you know doesn't have a drain valve either.

I've seen the aftermath of pressurized vessels blow. Just glad I wasn't around when it happened. And of those, they were just pressurized with water!

 

[Vlad D Impeller]

Re: What PSI are propane tanks rated for?

About four years ago, did you not consider to fabricate an air compressor using a propane tank?
What were the results from your assessment?

 

[ndemge]

Re: What PSI are propane tanks rated for?

SS is right... without the oil in the coolant, it's not going to last very long.

If you read up on on-board air systems, you'll find where a lot of guys will use an old car AC compressor for air. If you can get an old York, they had their own oil reserve. If you use a non-oiled type compressor, you need to add oil to the input side of the compressor, and then a seperator to take it back out (and this will have water with it)


I picked up a setup from a guy on craigslist a while back, it was compressor setup with TWO yorks, TWO electic motors and then an old Oxy tank as a pressure tank. When I cranked it into action, there was a lot of oil in the seperator, so I assume the yorks need to be rebuilt.

 

[bruceb58]

Re: What PSI are propane tanks rated for?

Extremely dangerous. Propane is very dry so little moisture is expected in a propane tank during its life. Not so with an air compressor filling it. The tank is not de-rated to account for any corrosion due to water.

 

[SS MAYFLOAT]

Re: What PSI are propane tanks rated for?

Its an accident waiting to happen.......thats what my shop teacher would have said....

 

[Scaaty]

Re: What PSI are propane tanks rated for?

I've made a few air tanks out of old P tanks, zero prob..

 

[ZmOz]

Re: What PSI are propane tanks rated for?

Oh for christ sake! A propane tank and an air tank are the same thing. The difference is a propane tank is thicker, and stronger. You can buy a kit to do this at most any hardware store.

Here's an interesting read.....
http://www.propanecouncil.org/files/10202_Battelle_Cylinder_Report_Final.pdf

Exactly what I needed. For those that didn't read it:
"Performance and integrity of the propane cylinders were established by burst testing each of the 236 test cylinders. The minimum design burst pressure criterion used here is 960 psi, or four times the service pressure of 240 psi, consistent with typical DOT requirements"

I only want to pump it to 300 PSI, clearly there is no problem there.

Before you charge one with air be advised it can turn into a bomb. YOU MUST Purge the tank (I use nitrogen) to make sure all the propane is gone. A small amount of propane will explode is placed in a high pressure (air) tank.

I'll be using a brand new tank, Costco has them for $22.

For safety sake, get one of those cheap air storage tanks. They are already set up with a relief valve, shutoff, and usually a pressure guage. Propane tank as you know doesn't have a drain valve either.

Cheap air tanks don't have a water drain either. Do you really think a chinese POS air tank rated for 125PSI is going to be safer than a DOT approved propane tank rated for 960 PSI? I already have a cheap chinese tank in the garage, I'm afraid to stand next to it when it's full of air. It looks like it's made out of 16 gauge sheet metal.

If you read up on on-board air systems, you'll find where a lot of guys will use an old car AC compressor for air. If you can get an old York, they had their own oil reserve. If you use a non-oiled type compressor, you need to add oil to the input side of the compressor, and then a seperator to take it back out (and this will have water with it)

I've already got an oiler/oil water seperator installed.

Extremely dangerous. Propane is very dry so little moisture is expected in a propane tank during its life. Not so with an air compressor filling it. The tank is not de-rated to account for any corrosion due to water.

Wrong, as usual. Propane tanks are thicker and rated for higher pressures than air tanks.

 

[Scaaty]

Re: What PSI are propane tanks rated for?

And I doubt very much that an old AC Comp will fill a 20 pounder to 300psi anyway..
Look at those little 12v air comp's..250 psi..takes an hour to pump up a car tire to 30psi

 

[bjcsc]

Re: What PSI are propane tanks rated for?

I've got on-board air in my CJ-7 that I set up with the old AC compressor. It was still working, but I never used AC so I adapted it to something more practical. I have a small tank (2.5gal) to keep it higher than the frame rails. It fills up to 150psi in about 25 seconds at idle...

 

[ZmOz]

Re: What PSI are propane tanks rated for?

And I doubt very much that an old AC Comp will fill a 20 pounder to 300psi anyway..
Look at those little 12v air comp's..250 psi..takes an hour to pump up a car tire to 30psi

Well, you're wrong. It has nothing to do with a cheap 12v compressor. It fills my 25 gallon tank to 150psi just fine rather quickly.

 

[bruceb58]

Re: What PSI are propane tanks rated for?

Since you already seem to know everything...why did you even bother to post?

My friend who is a mechanical enginer who does investigations of tank failures wishes you well.

 

[ZmOz]

Re: What PSI are propane tanks rated for?

Since you already seem to know everything...why did you even bother to post?

My friend who is a mechanical enginer who does investigations of tank failures wishes you well.

I've never asked for your advice, I already know you're clueless. And the only thing I asked was what the rated pressure of a propane tank is, which Xcusme answered perfectly. I do already know everything I need to know about compressors and air tanks, thank you.

 

[Vlad D Impeller]

Re: What PSI are propane tanks rated for?

Deja vu

 

[Scaaty]

Re: What PSI are propane tanks rated for?

Yeah, we are all wrong...but..it would be easier to..(whoops, why waste time..)

 

[POINTER94]

Re: What PSI are propane tanks rated for?

I work for a company that makes pressure vessels. Propane tanks come with a relief valve built in. I have seen what happens when pressure tanks explode. I have seen steel tanks, and fiberglass tanks. We burst test them everyday. I have also seen the damage one can do. Three months ago I saw a concrete block building knocked over (turned into rubble) and the top half of the pressure tank shot thru the roof over 100 feet in the air. I would have killed someone if they were in the building. It is figured that it had just over 200psi in it. 19gal tank was involved. I would shoot a guess that a propane tank is rated below 30psi when charged with propane, but I don't know. Vapor pressure of propane is like 185 psi.

I would agree that the post from Battelle labs indicates far better structural integrity than I would have thought, and Battelle labs are first rate, but I would never put 300 psi into a non-ANSI tank, the risk you will hurt/maim/or kill yourself or some unsuspecting spectator just ish't worth it. Do what you want, but just thought I would share.....