propane tank as air tank?

The concensus of what I've heard is that while propane tanks will stand the pressure, they are not as thick walled as tanks designed for air service. Thus they will rust out much faster if the air in them isn't thoroughly dry, something that's not to easy to achieve if you're planning on using them for air compressor storage tanks.

Unless you stand them upside down it won't be easy to add a water drain valve either.

I did use a 20 lb bottle for several years as an emergency "air pig" for occassionally filling a flat tire. I installed a kit I purchased for about $15 which replaced the propane tank valve with a new valve with a pressure relief, a Schrader (tire valve) filler port, and a 2 foot hose with a tire valve chuck on its end.

After reading comments to the contrary here and elsewhere I chucked it and spent $29.95 on a genuine air pig.

HTH,

Jeff

I'd try for an odd-ball vehicular propane tank, much heavier wall--try some propane distributors , see what they have and/or will refer you to an installation/conversion shop. calls to auto salvage yards might turn up something 20-30 gals. The little

20-40Lb tanks are too th> Looking to use propane tank either two 20lb or one 40lb tanks as air > tanks?

Swish around some oil? If you knocked off the valve, you could also get the water out... or drop a release in the bottom. Unless that voids the warranty of the pressure vessel, which I'm sure it does...

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

I use several 20# tanks as air pigs, no problem as the air is always dry. If I used them on a compressor I would mount them upside down. For an adapter I just bought a brass plug and drilled a hole and tapped it 1/4" FNPT

For portable air pigs I like the discarded Helium tanks of the same size but much lighter weight but the valve is not as good.

I use a 40# as an air pig - 20# is too small. Got it free at a refill station, as it was not OPD.

Got the mercaptan stink out with a little bleach, swished around and dumped out. I left the propane valve on and used a connector from a gas grill, with a quick-disconnect on it. I use a male-male adapter to fill. Put wheels and a long handle on it when it got tiresome carrying back & forth for refills.

They have a working pressure of 240 psi.

Bob

If you are buying new, why not buy air tanks?

Ron Thompson On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

The ultimate result of shielding men from the effects of folly is to fill the world with fools.

--Herbert Spencer, English Philosopher (1820-1903)

Go to the archives for any big-city newspaper and look up some of the spectacular air compressor tank explosions of the past. There is a reason why air storage tanks are spec-ed and certified.

The > Looking to use propane tank either two 20lb or one 40lb tanks as air > tanks?

I should explain (at the risk of repeating myself) that my skepticism about doing non-spec things involving compressed gasses, as expressed earlier in this thread, stems from about 50 years ago. I lost a friend in my scuba diving club when he carelessly used a cast iron 3/4" to 1/2" pipe thread reducing bushing to fit a "diving valve" to a CO2 fire extinguisher bottle. Lots of us used fire extinguisher bottles as diving tanks back then.

The threads on that bushing sheared the first time he was filling the tank and the valve blew out and hit him under his chin and continued into his brain, killing him on the spot. The poor guy didn't understand the shear strengths of different materials. He'd probably still be alive if he'd used a steel bushing, or maybe even a brass one, but he should have NEVER used cast iron.

I have the sand cast aluminum "license plate emblem" with our diving club's logo on it, which came from his car, nailed to my garage wall. I still think of him every time I look at it, even though I haven't had a scuba tank on my back for at least 40 years now.

Just my .02,

Jeff

Not all of them are. There are plenty of air compressor tanks and tire inflator tanks sold that are *not* ASME certified.

I used a brand-new propane tank as part of my air storage farm, since then I added a tire inflator tank. But I do know that I have an ASME hard-seat blow-off valve on the tanks.

Jim

Propane tanks are not "odd ball". They *are* compressed gas tanks, with DOT specs. Working pressure 240 psi, test pressure 480 psi, design burst pressure 960 psi. Depending upon the ambient temperature, propane in a tank is 110 - 130 psi, sort of. Single stage, home-use compressed air is generally not more than 100 psi.

Bob

Too thin walled? If thin, they'd not be ASME certified? I thought most air containers has them lined for rust protection?

Now, what about the true air tanks?

I have to replace that portable old horizontal tank, appox 10-12 gal with feet attached or portable tank with wheels removed.

I do have Graingers place on same block where our shop is but their price for a 11 gal portable tank with mount platform for compressor and motor for about 240 canadian. I think this is bit highway robbery. By the way this one is ASME certified.

How can I tell this pop-off valve is hard seat type? Graingers catalog leaves much to be desired on info.

Keep them coming, your comments are great!

New proper commerical quality portable appox 10gal compressor is over

1,600 canadian. Not the 600 home depot quality, we use it 6 days a week on all the time for ready air availablity. Our shop doesn't have this kind of money but I'm making sure this air compressor is done properly.

Yes I do have the air valve, air regulator, old shutoff switch that was hacked together. I rather get a new switch with manual switch cut off. Need to get pop-off valve!

Cheers,

Wizard

I've not cut into or looked into a air tank that had any coating on the inside. I'm not saying that none of them have a coating just that I've not seen one myself.

Wayne Cook Shamrock, TX

any ideas as to where to find such a kit to convert now days? Sounds like something that would work really well for me.

Any valve that you replace the origional valve with will be a lesser valve. Leave the valve in place, buy a mating POL fitting, hook it to a cross, add a schrader valve on one side, a pressure gauge on the second side and your discharge hose on the third and you have it made. Simple as it can be,

Even simpler, put a male air fitting on the POL propane fitting. You can read the pressure by putting a standard tire pressure gage against the male QD and can use the tank by attaching a hose with gage, air chuck, and matching female air fitting. Refill the tank using the standard air hose with female fitting when you remove the sir chuck.