15 hp compressor to 10 hp

[Dagny]

Have a nice compressor with a 15 hp 3 phase motor on it. I would like to put a 10 hp single phase motor on it. The comp. has a 15 inch pulley on it which is about 47 inches circumference. The motor pulley dia. is 8.6 inch with a B belt this pulley takes a Q1 bushing the smallest pulley I can find for a Q1 bushing is 7 in. 15 pi is 47 in 7 pi is 21.98 8.6 pi is 27 Am I right looking for 33 percent reduction in speed this pulley is not quite small enough?

 

[Dagny]

Sorry there is no oil in comp also no centrifugal unloader.

 

[larry_g]

15/8.6= 1.75

15/7= 2.14

1.75/2.14=.81 or a 19% reduction in speed

That said you need to find the specs on the compressor head. Are you sure that the compressor is capable of being run with a 10hp motor? Will it run at above min speed with a 10hp motor? Is the 15hp motor the original? Can you do a speed change with the motor swap to avoid the odd pulley swap?

Just some things you have to be aware of if you not already.

lg
no neat sig line

 

[Strouty]

Are both motors the same RPM? Most compressors that run on 15 HP should be capable of running on 10 HP without issue, but the manufacturer will have more specs and then you will know what the slowest RPM and fastest RPM you can spin.

 

[mike in tucson]

How many amps does a 220 VAC 10hp single phase motor draw? I thought I was pushing it with a 7.5 compressor.

 

[Strouty]

about 40

 

[Dagny]

Thank you guys if I figure out how to get pictures from my phone to photobucket I will post some pics. Almost positive 3 phase is original the motor can be 10 hp at 50 hz and or 380 volts but it was ran on 460 60 hz 15 hp. RPMS 1725 or so

 

[Mr onetwo]

If you run it below minimum speed you will kill it pretty fast.

 

[Norcal]

How many amps does a 220 VAC 10hp single phase motor draw? I thought I was pushing it with a 7.5 compressor.

220 is a 50 hertz voltage. NEC table 430.248 lists a 10 HP 1Ø motor at 50 amperes at 230V which what is required to be used when sizing conductors for the motor even if nameplate amperes are less.

 

[Strouty]

 

[md21722]

Circumference is not used in pulley or shieve calculations, only the diameter

For the 15HP motor,
8.6/15 * 1750 RPM = 1003 RPM

For the 10HP motor,
you'd likely want to run the pump around 670 RPM

670/1750 * 15 = 5.75 shieve

Certain pumps like IR T30's tend to run at higher RPM's, but many run 480-900 RPM.

What pump are we taking about?

 

[Norcal]

Still have to use the NEC table amperes, NOT nameplate.

 

[Dagny]

ol16 model no ser. 30t

 

[LS6 Tommy]

IMO you'd be better off buying a new or good used, smaller compressor. It'll probably be less expensive than a 10 HP 1 phase motor...

Tommy

 

[StevenMorgan]

IMO you'd be better off buying a new or good used, smaller compressor. It'll probably be less expensive than a 10 HP 1 phase motor...

Tommy

Those who've gone this route beg to differ. Mine had its 15hp 3ph motor stolen for copper... I bought it and the tank for $300. Add a $700 10hp 1ph baldor and $200 in motor starter and wiring...

$1200 invested over a years time (to keep the costs under cover from the wife) and I've got a compressor that puts out 42cfm all day long on less than 40a @ 240v.

Here's my wiring setup http://www.garagejournal.com/forum/showthread.php?t=309088

 

[StevenMorgan]

Dagny, do you know what pump you've got? You should be able to find a manual that tells you the rpm for different hp motors... That's what got me to where I am.

 

[Dagny]

model OL16 serial 30 T There are two of these compressors mounted on one big tank . I will only use one unless I wear it out then i'll have a back up. manufacturer Ingersol rand

 

[Strouty]

Are you sure about model and serial? Might it be a T 30 and have a serial number of OL16? Can you get us some pictures?