compressor leak.

Grallert

Hi all I have a 30 gallon compressor tank with a leak. Not really surprising as it was installed in 1959. My question is what kind of compressor should I, can I replace it with? Do I need a unit specifically made for pneumatic HVAC systems? or can I use regular compressor? My main concern is noise. The system it's running is relatively small, maybe 12 ancient Johnson Sylphon actuators. I have a system pressure around 80psi stepped down to a night and day pressure. I like the California Air Tool products but I only see 20 gallon tanks. Cost is a consideration as well as noise levels. I'm looking for input and resources.
Thanks for any ideas.
M

ratio

I've used a big box air compressor as a temporary air source until I could replace the compressor on my pneumatic system, but even with the pressure & differential cranked around to match the pneu. system it's didn't fare well. Lots of oil blowby, etc., but OTOH it did make it a year or so until I got around to making the correct repairs. It turned out to be about the same to rebuild the compressor (Toledo IIRC) as it was to buy a whole new compressor assy (drop in, motor and all), so that's what I did (& now I have a garage compressor as well!).

Can you replace just the tank, maybe even in a different location? If the compressor is in good shape, that might be the cheapest fix, at least kick the can down the street a few years.

Grallert

The motor and compressor are working fine, it's only the tank that's an issue. the compressor is as old as the tank is though. I did talk with the outfit that made our fire suppression dry side compressor and they were hesitant to provide a tank for such an old system, not sure why. My present tank is maintaining 40 psi on the system but that's at 100% run time If/when it fails I will connect our shop compressor up but is way too loud.

ratio

You might be able to silver solder the hole closed to buy a few more days of hunting a tank up.

Maybe Craig's List an old garage compressor?

EBEBRATT-Ed

Tanks are readily available. WW Grainger, Northern Tool. You could probably find one you could mount your compressor on.

JUGHNE

I service a 1961 Powers system with the original tank and compressor. The compressor might have been rebuilt maybe 20 years age. There is an cooler chamber/water separator between it and the tank. From reading about the AC for pneumatic systems they were meant to be slow to give cool, dry and oil free air.

Any tank would work as long as it has a tank-installed pressure relief valve. Bigger is better in this case. Of course you want water drain valve off the bottom.

Maybe somewhere it is stated it must be an ASME tank? I don't know, depends upon your application.

FranklinD

I recently bought a new compressor for my garage. I wanted one that was quiet and light enough to move (on wheels). I ended up spending the cash on a Quincy. 33 gal vertical tank, cast iron cylinder, belt drive, pumped oil lube system, 120v motor, adjustable pressure cutoff and comes with a regulator/drier if you want to use it. It was not cheap compared to Craftsman and big box store brands...but holy heck is it QUIET. The first time I ran it, I thought the belt was off or something. It’s THAT quiet. I don’t quite remember the ratings but I have no issues running a 3/4” impact gun, air hammer, cut off wheel, die grinder, etc off of it. Maybe 7-8cfm @ 90psi?

ratio

My pneumatics compressor also has an automatic tank blowdown valve, and a cooler-style air dryer. It's not what I'd call quiet, but it sounds nothing like a big box store model.

pecmsg

New air compressors are oil less, quiet, Much less energy usage, speed driven with driers built into the cabinet.

Couldn't imagine using the old style belt driven models anymore.

Grallert

Thanks for all the replies guys. For the time being I'm going to send the compressor line to our shop tank. From there it'll go back to the system line. I wont be pretty but it'll work. Then I wait for the finance and operations office to fund my new compressor.
One of the reasons I'm more interested in a whole new unit is so I can shelve the old components as stand by in case the pump on my other pneumatic system fails. It's had a few pumps on it from the looks of things.

Grallert

ratio said:

You might be able to silver solder the hole closed to buy a few more days of hunting a tank up.

Maybe Craig's List an old garage compressor?

I have a patch now but I'm pretty sure the inspector would frown on it.

pecmsg

ratio said:

You might be able to silver solder the hole closed to buy a few more days of hunting a tank up.

Maybe Craig's List an old garage compressor?

That tank is a pressurized vessel, unless you want to get it re-stamped not worth it!

Leonard

If tank has a leak it likely is because of rust from water accumulation inside tank. Air tank is a pressure vessel, I wouldn't go patching it. If it decides to burst it can kill. Since you worked on it the liability is yours, insurance co may balk at paying. Pressure vessel during burst is similar to a grenade .

I once considered propane tanks since I believe relief value is set at ~ 300 psi, but was told they rust more easily than real air tanks. However I suspect real air tanks don;t have any lining , I looked inside a Craftsman air tank (~ 8 gal). Was heavily pot mark rusted,


Old BBQ propane tanks seem to be much thicker, maybe 2X. At least by their apparent HEAVY weight.

I thought about about removing valve and mounting them opening down , and providing for draining. That would help keep tank ~ dry, less rust. Maybe a 3-4 inch diameter pipe tee as a air/water separator maybe.

EBEBRATT-Ed

Agree with @Leonard I wouldn't patch a pressure vessel especially an air tank probably rusted from the inside.


There is too much stored energy there

ratio

Just thinking of an emergency repair, certainly not as a 'fix'. The bottom of the tank is probably rotten all the way around and a new leak is sure to spring up pretty quickly.

Grallert

Well it is an old tank. Not sure how well it was cared for over the years. I've been draining it regularly but the damage was done. My "patch" consisted of a hard epoxy puddy. It didn't hold well but the tank could maintain 40psi after. I'm now using the motor, pump and switch to fill a remote tank. not pretty but it works for the time being. A new unit is in my future. Early christmas.

Leonard

Sounds like all you really need is a new tank.

Problem is your "patch" does nothing to improve the structural condition of tank. That's where your risk of grenade shrapnel effects comes from. There is a design analysis called "leak -before -burst" to determine whether a pressure vessel will first burst, or first leak to give warning (of crack growth that can lead to burst).

IIRC high stress helps promote a burst before leak condition,. But metal's burst sensitivity factor comes into the equation too. Didn't do the calculations, Just heard of it when we designed some custom small 6,500 psi aluminum containers.

Bottom line is tank thickness has likely been reduced by rusting, that increases stress in remaining steel, pushes you closer to a burst condition.

Air tanks do burst with devastating results, so much so that some citys require them to be in separate cement block rooms, to protect lives if they fail.

I'ld make taking leaking tank out of service a very high priority.

IIRC a 100 pound propane tank is ~ 25 gallons. I once thought about pulling a vacuum on one to remove propane, then let air back in. Not sure how to get the stinky "oderizer " out. Heard some one say clorox, But I'ld do a lot of flushing then airing out if I did that. I know water and TIde laundry detergent doesn't seem to do much.

If pump is a good one being old might not matter, dad bought a used compressor and had pump rebuild in the 50's. We've used it most every day powering car body work tools till retired ~ 1985, we still keep it pressurized for changing tires. (150 psi, 90 gallon)

Grallert

That interesting information. Yes the pump is still good, nice and quiet. I've taken the tank out of service. The good thing about this system is if the compressor stops working the actuators will open causing only an over heat state. Then it's back to the condition I found here when I started caring for this system a few years ago and that was controlling the heat in the mansion with the windows LOL.

Leonard

I see 100 pound propane tanks free on craigs list occasionally. Rich people toss them when pressure date stamp expires, rather than have them restamped. Picked up a few nice ones that didn't appear to have rust or damage. Since propane is ~ 245 psi at 120 deg F I suspect operating tank at a reduced pressure of 80 psi would be fine , even if it had MINOR defect that prevented it from being re-certified for propane.

AIrgas Co said Welding tanks start off life as high pressure tanks ~ 3000 psi, then as they get old/weak and don't pass hi-pressure test, they get recertified for lower pressure uses. Eventually in old age as ~ 900 psi CO2 tanks.

Don't know but I suspect propane are made of same steel as compressed air tanks. If valve is removed and tank mounted upside down I suspect they will continuously drain so less likely to rust. Still needs a safty pressure release,

Would have to find a way to remove propane's stinky oderizer. Maybe a non-flamable solvent would get it out. Suspect a propane company would know how to remove it.