3Z413 Speedaire compressor motor sizing, single phase

by Rick
(Hastings, MN, USA)

I bought this compressor that came without a motor, so I have no motor specs, other than it was a 25 HP, 3 phase. My questions are what HP, single phase motor would I need to duplicate the necessary HP to run it? Can I run a lesser HP motor, with a smaller pulley than original on the motor end to produce enough power to run the compressor at a slower RPM? I realize the recovery time would be slower. Being a V-4. 2 stage head, at a slower RPM, I'm sure it would still produce the amount of air I would use as far as volume. Possibly lower the high pressure cut off, since that is when it needs the most horsepower? Smaller pulley on the motor is basically a gear reduction, creating more power by changing the "gear ratio". making more power from less HP, but sacrificine RPM on the pump. Sounds good in theory, but will it work?


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Bill says...

Rick, the motor and what specs I was able to find follow. It were me, I'd use the motor size that came with the original compressor.

25 HP Air Compressor

Air Compressor 25 HP, 91 CFM At 175 PSI, 230/460 VAC, 3 Phase
Grainger Item # 3Z413
Price (ea.) N/A
Brand APPROVED VENDOR
Mfr. Model # HRA25-12
Ship Qty. 1
Sell Qty. (Will-Call) 1
Ship Weight (lbs.) 1350.0
Availability Item no longer available
Catalog Page No. N/A
Country of Origin
(Country of Origin is subject to change.) Not Available

Cheers,

Bill

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need to change motor on speedaire 1Z938 - RPM question

by Lewis
(Greenville, SC)

1Z938 is Industrial Duty 2-stage 1.5hp 1ph 60gal tank

the factory spec sheet says 680 rpm on compressor
compressor pulley is 12.5"

old motor is original 1.5hp 1750rpm with 4.75" pulley = 665 rpm

I have a new 2hp 3450rpm motor & with 2.75" pulley = 759 rpm

Will it harm the compressor to operate at this new rpm ?

____________________
Bill says...

The only people that can answer that question for sure are the tech design people at Speeaire / Dayton / Grainger.

By increasing the speed of the pump you are stressing it at a greater level. The higher speed may interfere with the efficiency of the compressor in terms of its ability to ingest and compress air.

Will it physically harm the air compressor? Possibly. It were me, rather than take the chance, I'd modify the sheave sizes to get as close to the original pump speed as possible.

Cheers,

Bill



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pump replacement for 5z185

by Ken Christian
(Boulder City, NV)

I have an older 5z185 and the pump destroyed itself.

Just wondering if a replacement pump is available and if it is worth
fixing. It is a 60 gal 5hp upright 220v.

______________________
Bill says....

Ken, first talk to Grainger Supply. This is their product line. The model number you posted seems to be live so they should be able to help you out.

See the Speedaire page for the info you need to know about your air compressor before you contact Grainger.

Is it worth it? Depends on the cost of a new compressor versus the repair and reliability cost, doesn't it?

Cheers,

Bill

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