Anyone out there ever have any experience with an air tank that is leaking?
I saw an air compressor for sale for $100.00 on the side of the road, it has a fairly new 5hp 3ph motor. 2 stage cast iron air pump which was rebuilt in 2001. The only problem is an air leak at the bottom of the tank. Do these things have to be certified or anything? To me it seems that water was allowed to sit at the bottom and so it started to corrode. Maybe it is a sign of the tank rusting out and a bigger problem than its worth.
Any insights would be appreciated! I believe the unit was used in a garage and so it probably saw heavy use. My usage would be light duty in comparison.
Replies
TJ,
If this compressor goes up to 200 or more pounds, which I'm sure it does, it would seem to me that it could be reeeeaaaally dangerous to use a leeky tank. I have a new 3 phase 5hp curtis with a two stage pump and a 120 gallon tank, it's still sitting on the crate and I haven't used it yet. This compressor cost me almost $2,000 so it may be worth it for you to buy this compressor just for the motor and piston settup and look at buying a new tank. I'm sure curtis or any other manufacturer would be happy to sell just the tank to mount these units onto.
Good Luck,
Brian
Tanks always have a little water sitting in the bottom, so thats where they'll eventually rust out. If the tank wall itself is rusted through, the tank isn't salvagable because there is no way to repair it safely. It is possible to buy a replacement tank, but it probably isn't worth it.
If the drain valve is leaking, that is usually an easy fix, provided the valve isn't rusted in place so badly that it can't be removed.
If the guy had it rebuilt and is now selling it, the facts suggest that the unit is worn out and not worth buying.
John W.
If the leak is coming from the valve at the bottom of the tank, that's not a problem. Anywhere else on the bottom, do not use it until the tank is replaced.If it's the drain valve, let the air out of the tank, remove the drain valve, clean the threads, use pipe dope or teflon tape and reinstall. You might have to replace the valve itself. I would replace the valve with a lever valve , attach a short hose with a thread and barb connection. Then you can empty the water out of the tank easily. I use a length of hose about six feet that I empty out the window.
mike
I got about 10 more years life out of my Father In Law's old compressor by replacing the tank with an old galvanized water well tank. But, the compressor pump finally wore out so I got a complete new unit at Lowe's for about $350.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)
PlaneWood
If a water tank fails, the worse that happens is you have a mess to clean up. If a compressed air tank fails, it can explode with deadly results. For this reason air tanks are built to a much more stringent set of standards. You were taking a substantial risk using a water tank in a compressed air system.
John W.
I kept the compressor cutoff switch at 80 lbs. The water tank was rated at 120 lbs PSI. This was not the new style water well tanks. This one was galvanized inside and out and had about a 1/8" wall thickness. Weighed about 3 times that of a modern air compressor tank.
When a compressor tank 'rusts out' it will develop pin holes in the bottom of the tank. You will see water starting to drip. After the water is gone, you will hear the hiss of air leaking out the pin holes. Eventually the holes will get bigger till the tank will no longer hold air at sufficient pressure.
Due to OSHA standards, I think all modern pressure tanks are designed with at least a 2X PSI saftey factor. You should always check the manufactures stated design limit of any replacement tanks and run your equipment within those stated limits.
Are any modern compressor tanks coated inside to prevent rust???
PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood
As has been said; valves you can fix otherwise I would hope your life is worth more than $100 .Most times air tanks rust through as pin holes but if it ruptures around you, you are dead meat!!Air tanks don't have to be certified regularly only at manufacture unlike oxygen tanks.You may able to find a replacement that you can adapt from a portable air tank from an auto part store or the manufacturer.I got a new tank from a scrapped C+H compressor and mounted my cast iron pump (from a wheel barrow compressor) to make a stationary one using galvanised plumbing fittings
T J,
Look down into the tank through any top opening by removing a fitting.
Solder two long wires to a small flashlight bulb.
Tape the soldered end of the wires and the base of the bulb.
Attach the top ends of the wires to two flashlight batterys, (taped in tandom) by soldering and taping.
Hang the bulb down into the tank and peek into the tank.
If only slightly rusted, drill out the pinhole and thread the hole with a small 1/4"pipe tap.
Use dope or Teflon tape and install a new pipe plug .
ON THE OTHER HAND, if it looks really cruddy, deep six the tank and buy a new tank. In any event, reduce the psi adjustment on the pressure control switch. Steinmetz.
Thanks, thats the best advice yet. Sounds like you have done this before.
TJ, Actually I rigged up a lamp like that to repair a gas
water heater tank maybe 35 years ago. managed to keep it working for ten more years.
Back in the 1960's I bought a Worthington Air compressor pump for a 'song' I kept it a while 'til I 'came across' a suitable tank(30-40 Gal)Bought a 2 horse 220 volt motor, pressure regulator switch, gauges, safety blow off etc etc and assembled the whole rig in my one car 'Shop'. There it was used continuously 'til I sold the house 5 years ago.Used it for Spraying, dusting, tire repair, sand blasting. Probably set me back 50 bux not counting labor.Had to drain the tank yearly and it still performed all those years. Sadly, when I sold all my machine tools, I had to give it to a friend for his son's business.
(Still pluggin' away in New Jersey.) Steinmetz
If you have 3 phase power, a 5hp motor is worth way more than $100 even if you scrap the rest of it.
Check out the following link and determine for yourself whether it is worth the risk. This happens way to often - drain your tanks regularly.
http://www.doli.state.mn.us/airtank.html
Steve
I'd be a little cautious about pluging the hole in a tank with a threaded plug. Given the thickness of these air tanks, I'd guess that you'd have less than two complete threads holding that plug in place. If it strips, it becomes a lethal projectile. If you have the resources available, and the rusty spot is small, a pipe coupling could be added to the tank exterior (by welding), and a plug threaded into place. Water heaters and low pressure boilers are one thing, with 30 to 50# pressure, but compressor tanks may see 90#+, unless readjustment of the control is possible. Much safer to retire the leaking tank.
John in Texas
I second Tailsorpins opinion about putting a plug in a rusted through tank. The plug wouldn't have enough threads to be safe, especially in metal that is rusting away, and at close range the plug, if it lets go, would be quite an effective bullet.
If one spot on the tank is rusted through, the whole bottom is almost certainly rusted badly enough to fail elsewhere soon, and if it splits instead of developing a pinhole, the whole unit will become a missle.
John W.
Another cheap source for pressure rated tanks are propane tanks
Propane tanks have thinner walls than ASME rated tanks, and therefore are not suitable for use as a fixed air reservore. Bite the bullet and buy a NEW compressor and tank assembly. HOW MUCH INSURANCE do you carry for your future widow? Many localities and states require all tanks over 10 ga. to be ASME rated and for GOOD reason. Remember free things costs the most and this quallifies as one.
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