I Just Got a New Air Compressor

[Iplayfarmer]

I did some trading on Craig's List and ended up with a BIG air compressor. Now I just have to get it working.

The compressor head is a Ingersoll Rand 234. I've seen specs on the internet ranging from 10 CFM up to 19 CFM. My guess is that is depends on the size of motor that's on it. Right now it has a 2HP Baldor M3609 motor on it. There are two problems with this motor... 1) It's severely underpowered for that compressor head. 2) It's a 3 phase motor and I only have single phase power at my house.

What size motor should I get? I've added up my peak air consumption, and I think 12 to 15 cfm will give me plenty. I've tried to find some technical specifications on this compressor head, but I'm coming up with very little. I'd like to know the pressure range, torque requirements, and recommended RPM. I'm sure I can run this compressor on a smaller motor if I have the torque right. I just wouldn't get as much CFM. If anyone has a good source for tech specs on this compressor head, please post.

 

[unfinished]

I had one of those. I have a parts list that I got from the supplier of a reed valve kit when I had to replace them. Parts list shows 1.5, 2, and 3hp motors utilized for this unit. It is a two stage pump, should be around 150-175 psi.

 

[unfinished]

Army manual has 234C2 model, 610 rpm, 5CFM (which seems low)

http://www.liberatedmanuals.com/TM-5-4310-348-14.pdf

When changing motors, keep same rpm and frame type. Eitherwise you may need custom pulley size and mounting plate.

 

[Midniteoyl]

Looks smaller than my 30gal Sanborn with 3hp... I would say 3hp is max at prolly 6-8cfm @ that high PSI

 

[Iplayfarmer]

Thanks for the replies. I guess the consensus on a lower CFM is good and bad. Good in that a smaller motor will be cheaper, but bad in that I was so excited for lots of flow capacilty.

Is there some way to measure the capacity of a pump head?

If a 2hp motor really is the right size for this compressor, I may just pull the motor off my old Sears that has a bad compressor and use it for now.

 

[Stimw]

I can't tell from the pic but I'm guessing that is an 80 gal tank which means you will have plenty of air storage. Just make sure you don't have leaks and have a shut off at the tank.
I have a 5hp on a 30 gal tank and a 60 gal back up tank with shut off when not used if I need more storage. I have it set at 170 psi off 130 psi on and I never run out of air.
I would reccomend a 5hp motor, not one of the small motors you see but a real 5hp. The small motors rate them at "peak Hp" not true hp.

A lot of compressor manufacturers will use the same pump with different motor hp/pulley combinations and rpm. You could have a 5hp, 7.5 hp or a 10hp on the same pump with different size motor pulleys.

 

[BukitCase]

5 HP Single Phase Baldor Electric Compressor Motor 184T Frame L8430T 230 Volt | eBay

I recently replaced a fried (bearings, then armature) Baldor 5 horse on my 80 gal. 2 stage dev-air - the above is likely the best price you'll find, and that motor is a little better rated than the original on my compressor.

Also, the people on that link were very helpful and I got the motor in 3-4 days to the west coast. (free shipping, too - if you think this isn't important, try LIFTING a 5 horse REAL motor :=) Steve

 

[BukitCase]

Sorry, forgot to mention - if you move up to a 5 horse, or even 3 - you'll need to get one of these while you're at it

New 5 HP Single Phase Magnetic Starter Motor Control | eBay

Same people, one stop shopping

Without a motor starter (contactor) you'll be replacing the pressure switch REALLY soon... Steve

 

[Midniteoyl]

80 gal tank???? Looks smaller than that!

 

[Iplayfarmer]

I do have a few very nice hazardous duty mag starters that I can use, so that's not an issue. (I'll trade you a few nice hazardous duty mag starters for a good 5 hp single phase motor.)

I looked at the motor that's on my other compressor, and it's only 1.5 hp and it's a 3600 rpm motor. That won't work. I have another short term solution, though. It's a 1.5 HP single phase motor that is 1800 rpm. It's an old beast from back when horsepower was really horsepower. The problem is that it's turning the wrong way. If I can get it to turn the right way I may not get lots of air out of the compressor, but the compressor will be quiet.

How do I reverse the direction of this motor. It has a green, black, red and orange wires. I've attached a picture of the plate. 220 volt wiring includes the red and orange wires connected to each other with the black to L1 And the green to L2. This turns the motor clockwise. I need it counterclockwise. (110 volt wiring includes the black and orange to L1 And red and green to L2). Do I connect the black and green together and connect the red and orange to the hot wires?

 

[BukitCase]

It doesn't look to me like that motor CAN be reversed - all I see on the nameplate is the option of 110 or 220 volt hookup. You're right about the age - I haven't seen 110 instead of 115 or 120 on a nameplate for about the last 45 years or so.

Only way I can think of that might get you by is REALLY rube goldberg - you'd need to fab a mount that would hang the motor out the BACK side of the compressor motor mounting rails, and flop the motor around so it's driving the air pump from the opposite side.

When the motor went out on my compressor, I found the exact same 5 horse Baldor anywhere from the price in the posted link, all the way up to $1000. Those motors have a terminal box on one side that's about 4" x 6" by 2" deep - the cover plate on it lists strapping for 120, 240, CW and CCW options. It also has double capacitors that I think may enter in to the direction choice, don't recall now (I was just happy to have air again :=)

Wish I could offer more help, but I know you don't want MY "extra" 5 horse - all THOSE horses aren't even worth makin' dog food out of any more... Steve

Oh, switching the two AC wires won't change anything - you either wire it for 110 or 220. Doesn't matter whether (for 110) the neutral or the hot goes to L1 or L2. For 220, L1 and L2 are both hot. In either case, your power cord should have its green wire hard wired to a lug on the motor FRAME.

You might want to double check that the frame is NOT tied to either pair for 110 operation - I'm not sure about some of the older stuff having both L1 and L2 isolated. An Ohm meter will let you know for sure - you want NO continuity between ground (frame) and EITHER L1 or L2.

Hope this helps...

 

[Iplayfarmer]

I agree that there is not an easy way to reverse this old motor. I'm convinced, though, that somehow it can be reversed.

The point may be moot now, though. I found a 5 hp single phase motor at work sitting on a shelf in the back all covered with dust. I've talked with the powers that be about making some kind of trade with what I have. It sounds like I'll probably be able to work something out.

 

[Iplayfarmer]

New question... If I can get this 5 hp motor how do I determine what size of pulley to put on it?

 

[City Farmer]

Wouldn't it be easier to just get a single phase to 3 phase converter and use the exsisting motor? Surplus Center has them Surplus Center - 1 HP TO 3 HP PHASE CONVERTER
Or you can find them on CL fairly cheap.

 

[Iplayfarmer]

Wouldn't it be easier to just get a single phase to 3 phase converter and use the exsisting motor? Surplus Center has them Surplus Center - 1 HP TO 3 HP PHASE CONVERTER
Or you can find them on CL fairly cheap.

Well, for that matter I can induce a phase in the existing motor with a couple of large capacitors. I figure if I am going to buy anything, I want to try first to get a larger motor. Then, if that doesn't work, I will look into other options. I figure if I am going to take up shop space with a 5 1/2 foot long air tank, I might as well maximize how much air I can get.

 

[BukitCase]

Here's a link to an IR 2340, looks like just a newer version - shows specs INCLUDING motor rpm, pump rpm, pully (sheave) sizes, etc - should get you close, although you didn't mention whether the motor you're lusting after is 1725 rpm or 3650 -

INGERSOLL-RAND Air Compressor Pump, 2 Stage - Air Compressor Pumps - 4KR37|2340 - Grainger Industrial Supply

Mine has taper locks on the motor sheave, if you're not familiar with them you may need to "cut and try" a couple times to get the two pulleys co-planar for best belt life... Steve

 

[BukitCase]

Oh, here's a factory manual for the 2340, apparently it's used up to 7.5 horse - not a LOT of details, but may help

http://www.irtechpubs.com/ir_pdfs/C...ressors/Reciprocating Compressor/22607402.PDF

Sure LOOKS like just a newer version of yours... Steve

 

[Stimw]

A compressor pump doesn't care what direction it turns BUT the flywheel has a fan for cooling and oil system might not work properly.
If you change oil in the pump make sure you use 30W NON-DETERGENT. Walmart sells it, also NAPA.

 

[Iplayfarmer]

Thanks BukitCase for the Grainger link. That's VERY helpful. Those specs are exactly what I've been looking for. I'm especially interested in the max RPM and max psi specs. For a speed of 1745 rpm I'll need a pulley that's over 8". That's a big pulley.

The motor I'm trying to get is a 1740 rpm motor. The plant engineer needs to take a look at the motor tomorrow morning and make sure it's truly surplus and not waiting to be installed in some machine. Then it will be on permanent loan to me.

Stimw: I do plan to change the oil. That seems like a good idea for a used machine. Any other maintenance items that I should consider?

 

[BukitCase]

Those numbers didn't sound right, so I did my own math - with a motor speed of 1725, flywheel diameter of 13.75 and motor sheave diameter of 6-17/64 (all their numbers) you would get a pump speed of 786 rpm, NOT 1575.

My DevAir 5 horse (baldor, not toy) 80 gallon upright compressor has a motor sheave that's about 6-7 inches and a flywheel that's around 16 inches (too lazy to go measure them) which would put the pump speed at around 700 rpm, and it puts out 19-20 cfm @ 175 psi - I'm guessing the DeVilbis pump must have a different bore and stroke, but SOMETHING's not adding up here -

I think the reason your old motor sheave is so much smaller is so the smaller motor can drive that pump, but the discrepancy in Grainger's numbers bothers me.

One thing's for sure - if you go with the 5 horse, you're most likely gonna need to fab a new belt guard once you've got it dialed in... Steve