Compressor

[Stlmowerguy]

Need some help with an air compressor.

I picked up a running 80gal IR 2 cylinder air compressor. My company upgraded our compressors to 2 screw drive 120gal units, which left our 80 gal up for grabs. Picked up both for free. One has already been turned into a new smoker, which leaves the IR 80gal. The down side is that the motor is a 3 phase motor. Great for the warehouse, but no good at home.

I am going to just replace the motor with a single phase 5hp motor. I know I can get one on e-bay with the same frame, hp & rpm for around $400 shipped. Looking at CL tonight though I found someone who has a 5hp Baldor but it is 3450rpm instead of 1750rpm.

Existing motor: 3 phase 5hp 1750rpm, 8" pulley
Pump: IR 2475 w/14" pulley

Question 1: What size pulley should I put on the motor to keep the pump speed the same?
Question 2: I have a magnetic starter, do I need to just replace the heaters in order to step down to 1 phase? Anyone now which p/n? Would like to keep the existing starter.
Question 3: I think for the magnetic starter wiring I just need to wire to leg 1 & 3. Correct?

New motor:

Pictures of current compressor:

 

[The Cobbler]

your pictures are huge!

 

[Stlmowerguy]

I just fixed it, sorry about that

 

[THF409]

Check out surpluscenter.com for compressor motors. They should have what you're looking for.

 

[Stlmowerguy]

Thanks but I already found a motor. Need to figure out the pulley size and starter info.

 

[scottwilson26]

Attached is a link to a pulley calculator. I think this will work for your sizing issue. Good luck! And great steal on an awesome compressor.


Sent from my iPhone using Tapatalk

 

[larry_g]

If you double the motor RPM, then you 1/2 the pulley size. If you have a choice on the smaller pulley of going a bit over or under 1/2 the size because an exact 1/2 size is not available then go smaller. The 3450 motors do not have the torque of the slower motor so going to the smaller will be to your advantage.

lg
no neat sig line

 

[md21722]

In addition to different heaters, if the has phase loss detection, it will need to be "looped" meaning the load side of one phase is fed into the line side of one of the unused phases and then you take the motor load from there. Not sure what the heaters cost, but you can get a new Square D starter on eBay for about $120-130. There is nothing special about that Furnas starter. The other thing you can do is buy one of those cheap Chinese VFD's off Ebay for about $260. There is some programming work, but then you can keep the existing motor.