So I'm looking for some opinions on a compressor that I'm trying to set up in my garage to do general automotive work, but most importantly will be running a DA sand quite alot to finish some bodywork. It's a rather pieced together setup from what my father was able to grab from a division of his company that was closing down. Got everything hooked up and unfortunately the 80 gallon tank that it came with has a crack by one of the feet, must have been damaged at some point during shipping. I can't afford a whole new tank yet, itd be about 700 shipped for a very similar 80 gallon. I picked up just a tank locally for $150. The motor is a 5HP and the pump is rated at 19CFM. Now I know I will have more cycles, but shorter cycles than with the 80, but will that take a toll on the parts after some time? I would like to get another 80 gallon for it down the road but would really like to get the car finished up first. Any opinions are greatly appreciated, thanks.
Air compressor question
- Thread starter gsir08
- Start date
redmondjp
Well-known member
You neglected to say what size tank you picked up locally - a 60 gallon maybe?
If so, run it and see what happens. If your compressor is really 19CFM, that should be able to keep up with one sander pretty well.
If so, run it and see what happens. If your compressor is really 19CFM, that should be able to keep up with one sander pretty well.
Oops, I did leave out that very important part, the tank I picked up is a 60 gallon. Since I'm downsizing the tank I'm sure I will still have the same output that the 80 would have as far as overall air use. My main concern is will it damage the motor and pump going to the smaller tank since it will be cycling on and off much more.
The pump/motor will be fine, post some pics. 
gdocktor3
Well-known member
You could have just had the crack welded. Then you can tie the two tank together and have 140 gallons of air on tap.
Just use the 60 gallon for now. Junk the 80 gal since is has crack.
Be on CL lookout for Oil-less Crapsman compressor that bit the dust. A 20 or 30 gallon tank over by your heavy-air tool (ie DA sander) will give you extra flow. Build proper airline system of copper or black-pipe steel and you'll be all set !!
Be on CL lookout for Oil-less Crapsman compressor that bit the dust. A 20 or 30 gallon tank over by your heavy-air tool (ie DA sander) will give you extra flow. Build proper airline system of copper or black-pipe steel and you'll be all set !!
That is definitely an option, of course that would require complete disassembly, which would set me back time wise on getting this thing running. Also having a tank welded makes me a little nervous, but if its done properly there shouldnt be anything to worry about.
Make sure you do not exceed the max pressure limitations of the new tank. That pump may be capable of 175psi or more and those craftsman tanks are usually only good to around 150psi. Adjust your cutoff switch to reduce the shutoff pressure.
A few more cycles is not going to hurt that pump. You will likely be running it continuously whether 60 or gallons doing DA work. Don't worry about it.
DO NOT FOLLOW THIS BAD ADVICE. You absolutely did the right thing finding a replacement tank.
This is what I was hoping to hear, and yes that was one of the drawbacks unfortunately, 80 gallon was 200MAWP, 60 is 150. Was going to set the pressure for 160 on the 80, I'll turn it down to somewhere around 140.
Roberts210
Well-known member
Ditto on NOT having the tank welded.
bsaint
Well-known member
Did the weld crack on the foot or on the tank? If you cracked the weld on the foot, I would've just welded it but I trust my welds.
TigerDude
Well-known member
Welding a pressure vessel can be done, but it really should be someone who does such things for a living, not a general welder. There are ASME codes for such things.
I wouldn't want a bomb in my garage.
I wouldn't want a bomb in my garage.
texasfiremedic
Well-known member
Maybe I just don't see the problem in welding the crack on the tank. The foot was welded in the beginning to the tank. yes, it was welded to the cap's exterior and not welded to penetrate all the way through. If you were to weld it and the hydro test it again above working pressure maybe 1.5 time working pressure then what would be the problem?
Essentially, the tank is made of 3 pieces, a top, bottom, and outer shell and these form 3 seams. All those seams are okay, and the feet are attached with weld to the bottom cap. The way it cracked, looks like the foot got smashed putting severe strain on the bottom cap causing it to crack. So maybe you could remove the foot, grind everything down and seal that crack, then weld the foot back on, but that will be its weak point, I'm not a certified tank welder and to get one to do it would probably cost as much as a new tank. It's a 30 year old tank, sure it may work for another 10 years with weld on it, but for $700 its worth the insurance of a brand new tank. Just can't scrape together those funds yet.
G_P
Well-known member
It could be welded and recertified, but the cost would likely be prohibitive.
Turn the old tank into BBQ, smoker, or fire pit.
Turn the old tank into BBQ, smoker, or fire pit.
You could put bearings on each side and use it for a lawn roller.
Boilerhouse
Well-known member
Best practice would be to also match the safety valve to the max psi rating of the tank and compressor volume, so in this case a safety valve set to relieve at maximum 150 psi and the full (or more) compressor volume.
gdocktor3
Well-known member
I'm not going to make a big deal out of this, but don't try to put me down saying I give bad advice. I generally speak from my own experiences on stuff like this. He already bought the new tank so I knew he wasn't going to fix it anyways. That's why I joked and said to tie them together for 140 gallons. Anyways, here's a picture I just took. It's my 30 gallon 5hp compressor, that I use all the time, 130 psi of pressure, with a crack on the bottom that I welded about 2 years ago. No leaks. No explosions. No second guessing or worries when things are done correctly. Goodnight, good luck and Happy Easter.
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marinusdees
Well-known member
Amen.
So now I have a new issue at hand, I've become absolutely paranoid about air compressor tanks. The one I purchased, although its in much better condition, it is still an old tank. Ive cleaned it all out and thoroughly inspected, and have found that the bottom of the tank is missing some chunks that have rusted away. Now, it hasn't rusted through to the point where there is holes, but it is significant enough to notice when looking into the tank. Underneath looks great, and the all seam welds are perfect. The only issue is the fact where the bottom of the tank is pitted a fair amount. So what do I do, try it and if its not leaking I should be good for 2-3 years until I'll have some spare cash for the new tank. Or stop messing around, and don't do anything except get a brand new 80 gallon for 700 dollars. After all this research I'm paranoid that anything except a brand new tank is going to blow my garage to bits.
Keep in mind, I just bought a house less than a year ago, money is tight at this point in time, but still safety first. So where do I draw this line....
Keep in mind, I just bought a house less than a year ago, money is tight at this point in time, but still safety first. So where do I draw this line....
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redmondjp
Well-known member
Have you read any of the threads on air tank hydrotesting on this site? You can do it yourself, for a nominal cost (of the few fittings and such that you may have to go and purchase). This would be a good way to put your mind at rest.