I have a Craftsman 30 gallon 5 horsepower 110 volt air compressor. It puts out 6 cfm at 90. I would like to be able to paint and do more such as sandblast. Could I get another similar sized compressor and hook the both togther or do I have to break down and just buy an expensive bigger compressor?
I have 3 hooked together and they cycle as demand increases or decreases.
They would need to be on different breakers.
i
Boy, those sears horses are getting really small. 5hp on 110 and it only gives you 6 cfm?
To answer your question, putting two together is a good idea for those heavy use jobs. I gang my 7.5 two stage and the tractor PTO unit for sandblasting.
Karl
Well ... given that 5HP on 110V would draw over 30A, and most duplex wall outlets are fused for 15A, with some heavy duty ones fused for 20A -- exactly how are you supposed to get 5HP out of a 110V outlet? :-)
Enjoy, DoN.
yes, you can hook compressors in parallel.
but let me point something else out to you - your compressor is called 5 HP, and puts out 6 cfm. I have a crafstman compressor (that I no longer use) - it says "2 hp" and it puts out 7.2 CFM at the same PSI. What does that tell you..... it tells you that you are not getting a real 5 HP compressor. Moreover, at 750 watts per HP (minimum), 5 HP would be 3750 watts, which at
110V is 34 amps - I'll bet your compressor doesn't draw more than 20 amps. So, Sears lied to you about the compressor.I also have a 5 HP compressor, made by Quincy - it weighs about 850 pounds and puts out 21 CFM at 160 PSI.
Moral - beware of high horsepower cheap compressors. What you really have is a 1 hp compressor with an oversized motor. You will be happier if you can find a surplus or used "real" compressor - look for a large compressor with two pistons and a belt drive, look for a real 2HP motor - should draw
15 amps (for two HP) continuous at 110. Or if you can wire for 220, go to a 220V compressor - you will get a better unit and will be happier.** Posted from
What is a tractor PTO unit? I dont knwo if I have seen on eof those?
What is the correct way to hook up more than one?
Simply an air compressor ran by the tractor. Make your own or buy one. If you've got a tractor, its stupid to have a gasoline engine compressor unit.
My main use is for pruning.
Karl
Karl Did you build your own? I have an old Jeager compressor with a dead 4 cyl Continental that I have been thinking about rigging to run with a PTO. I would like to get the compressor to run at least 1000 to 1500 rpm. My Oliver
88 has a 550 rpm PTO and I have been looking for some sheaves to do this with V belts or a 3-1 gearbox. Steve
Break there. You have a "5 SEARS Horsepower" compressor. "Peak HP" is not the same thing as actual HP - it's what the motor will put out when so overloaded it's almost stalled, and right before it burns up.
For a 110-Volt model, if you do the math on the running amps it's more likely a 1 real NEMA rated HP. You can't really get much more on a 120V 20A receptacle circuit - 1 HP at 120V draws 16A, to get more power you have to go to 240V and/or hard-wired units.
Here's a clue - when you find the HP Rating box on the motor maker's nameplate is filled in with "SPL" - Special. They won't lie for the marketing folks at Sears, so they leave it blank.
Either one. If you hook two units together with a hard pipe make sure they are roughly matched. You can NOT simply parallel the tanks between a two-stage permanent compressor running 175 PSI in the tank and a little portable that stops at 110 PSI - the two-stage will keep running and pop off the safety valve on the portable.
You could parallel two units after the output pressure regulators, and with check valves so the high pressure unit can't backfeed into the receiver tank on the portable.
And remember that electric motors on compressors should not be cycled on more than about five times an hour with a minimum 5 minute running cycle, or you can burn up the motor - every start uses 'locked rotor' current draw to start the motor, and it takes running for a while to let the cooling fan draw that heat out of the windings. One short cycle a day won't kill a motor, but dozens a day in rapid succession sure will.
When sandblasting or doing other high air draw jobs it's better to let the main compressor just keep running to keep up, don't start and stop and force the compressor to short-cycle - do NOT wait for the compressor to catch up and stop then start blasting again right away. Much better to stop for a minute and watch the tank gauge, and when it is approaching normal start blasting again and let the compressor stay running...
This is why commercial units can be ordered with a constant-run unloader system, just like a gasoline engine compressor. The motor keeps running and stays cool while the compressor isn't working, and the power draw is minimal (but not zero) with no work performed.
For factories this makes much more sense than stopping and starting the motor several times an hour, with every start surge counting against the KVA rate meter for the utility. (The higher the peak power you use, the higher the KWH rate for the power.)
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Bruce L. Bergman fired this volley in news: snipped-for-privacy@4ax.com:
Yeah... A friend gave me a fairly new Huskey 5HP (110v) job because "It runs slow".
I peeled off the covers to discover a interestingly built pump (which I saved for other things) and a motor no larger than my fist. This thing was wound with only a few dozen turns of about #16 wire, had less metal in it than a good syncronous clock motor, and had one lobe of the armature completely shorted.
He had about ten total hours of USE on the compressor... probably 30-40 minutes of run-time.
These things are more junky than cheap vacuum cleaners.
Now... the 26-gallon tank on wheels with a "space saving" stand-up feature made a dandy portable air tank. I actually have a large enough porta-air now to get my tractor limping back out of the pasture if I get a flat.
LLoyd
The Bador website does not list any either.
The venerable Baldor L1408T, which is 3 HP, uses 32 amps. The 5 HP equivalent of that would be 32*5/3=53 amps.
iOn Wed, 14 May 2008 06:28:32 -0700 (PDT) in rec.crafts.metalworking, stryped wrote,
A Tee fitting.
Ayup. Just use a double pulley and belt. Step it up 4:1 so you can leave the tractor just a crack over idle. A 100# LP tank makes a great air bladder.
Karl
This one is still in the trailer. The tank, controls even a jack hammer is still there. Steve
My pieced-together smaller compressor has one female quick disconnect directly from the tank and a second one after the regulator. I made this pipe cross adapter to connect it to another larger compressor or a portable tank;
O O is pressure gauge #4
v v male QD #1
A cross is like a tee but with four legs. You could use a tee and omit the gauge.
Close the valve and plug QD#1 into the tank of the smaller compressor. Plug an air hose from the larger compressor into QD#2 and open the valve to connect them. Close the valve before unplugging.
The portable tank has a female QD in the outlet. Plug QD#1 into it to fill and use the tank. Fill from QD#2, draw air from #3.
The highest pressure shutoff setting in the system has to be less than the lowest safety blowoff valve. On mine the large compressor shuts off at 120PSI, the smaller one's relief opens at 125, which is probably too close.
The small one has a true 1/2HP motor belted to draw 8-9A at shutoff. I can sandblast continuously with it at 50PSI, using the large compressor's tank as a reservoir (the large one runs but needs more work). The pressure slowly drops while blasting and recovers to ~60PSI while I fill the cup.
This is an updated rehash of my first RCM discussion with Fitch about
15 years ago.Jim Wilkins
PTO = Power Take Off.
It is a spline rod sticking out the back end of the tractor and from the massive transmission. With the tractor at full stop and brakes on, one can attach the pto to another unit and when the PTO rotates it does something.
PTO's often turn blades or rotating things. Mowers and ....
Martin
Mart> >>
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What is the correct way to hook up more than one?
*********************************************Mine all just connect to the main 1" pipe that feed the whole shop. They all have ball valves on their output. One has it's pressure switch at 65 low/110 high, one set at 70/110, one at 80/110. (if I remember correctly, it's been years) If #3 kicks in, we're using a LOT of air. 90% of the time only one compressor is running.
You probably should shift the setpoints around every year or so, if the compressors are similar, to balance the runtime (logic changes if they are different sizes.)
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