IR T-30 2545 quick Q

[Spyider]

i was TRYING to talk with Ingersoll rand help.. anyways if anyone everytryed that dont waste your time apparently lol.

I got this compressor it has the 10hp 3ph motor on it. clearly that has to go..
looked around and called and i found a 7.5hp AO Smith (k311m2) motor at a local engine shop, i was told i can pick it up for 640$.. same frame same shaft size, slightly longer.. no big deal (has TEFC where the IR has OLP).. so seems better their also. both spin in the 1800 RPM range.

Now my Q is i see people say if you change motor size i need to change sheave size also.. wasnt sure if i had to since its spinning the same speed.. And if i need to how would i figure out what size for a new one to get?

In my owners manual it has "pulley,Motor" sheave numbers
10hp- 32202392
7.5hp- 32121683

do i simply have to find one the size of the 7.5hp part number?

looks like:
10hp = 10.6x1.375
7.5hp = 8.6x1.375

i dont know help me on this lol if i dont have to buy one i dont want to spend more on it. does anyone know what RPM my pump should be spinning at.. or if theirs a calculator online to use to figure that out for me lol.

 

[Spyider]

looks like the pump rpm should be 825-1050. im gona go outside and measure the wheel on the back of the pump then.

 

[Spyider]

Compressor - 18"
motor - 11"

those are close, might not be 100% was cold out their and hard to get at haha.

 

[Spyider]

Most industrial pumps recommend 850 RPMs. To calculate shieve size use to following formula
Sheive(motor pulley) = 850 x 18 / motor RPM
18 is my pump shieve size
X= Motor shieve size
X= 850(18)/ 1800
X= 15300/ 1800
X= 8.5 looks like the 11" might be to big then? .. possibly?

But if im keeping it the SAME rpm.. i dont see why i cant leave it? lol anyone?

 

[tcianci]

You need to understand the whole compressor. The pump presents a load to the motor. i.e. it takes a certain amount of torque to run the pump. The NO LOAD speed of the original motor and the replacement motor may be the same but, when you attempt to run the pump with the motor with lower power, the smaller motor will not be able to run within it's designed rpm range since you're taxing it with a load that originally required more power to maintain the designed speed. That's why the manufacturer specifies a different diameter sheave for use with the smaller motor. Going back to understanding the compressor as a whole system (pump, sheaves, motor) you will find that there is an associated de-rating of the overall capacity of the compressor because you're powering it with a smaller motor.

 

[matt_i]

I would look at it like this, you took a 0.75 multiplied reduction in motor HP.

I would take a 0.75 multiplied reduction in sheave diameter.

So your 8-8.25" pitch diameter or OD would be about right.

There's more to it than that, but that should get you where you want to go. Always recommend QD or SDS taperlock sheaves with the appropriate bushing for your shaft size, and use a torque wrench to set the taperlocking bolts.

 

[Spyider]

ok at least im on the right track it would seem then. i also plan to lower the pressure from 175 to 130-140..
i was looking at granger for the right sheaves but their so much their lol kinda confusing to find the right one. (8.5")..

 

[matt_i]

Look at a Martin Sprocket or Browning sheave catalog online. You (probably) want a single groove sheave. If you spend some time it will be obvious.

 

[Spyider]

http://www.amazon.com/TB-Woods-Section-Bushing-required/dp/B003N17MMW/ref=sr_1_1?s=industrial&ie=UTF8&qid=1460171323&sr=1-1&refinements=p_item_pitch_derived%3A8.5+inches

seems like thats about the size i need for OD.. ide assume that the shaft hole that large its like a taper fit bushing.. sorry if these seem like dumb Q's its just i havent done anything like this before. i know i can do it just want to make sure im looking at the right stuff so im not throwing money away..

 

[Spyider]

ok, so i found a good price on a local motor place.. 7.5 hp ill be ordering tomarrow.
i also will be getting a pulley at the same time from them. however.. they only have 2 sizes that are close to the 8.5" that would be ideal. (both are taper lock bushings)

the sizes are:
7.75" with would spin the compressor at 750 RPM
8.95" with would spin the compressor at 870 RPM

ingersoll rand said this compressor Min/Max RPM : 612/1050..

So ithor size would work ide say.. what would you chose..? i dont know lol.

 

[aptdweller]

Just a quick comment here: 10 hp, 1800 RPM and a 18:11 ratio is equivalent to 825 RPM on a 7.5 hp 1800 RPM motor.

We don't really know what factor of safety IR used for the original combo, but you might want to err on the side of the smaller pulley just to keep from overtaxing the motor.

 

[Spyider]

Ok. In that case the 8.95" one will be much closer at 870rpm.. Ide think that should be a good size combo to make it all run smooth..

 

[stonesfan68]

In my owners manual it has "pulley,Motor" sheave numbers
10hp- 32202392
7.5hp- 32121683

Do I simply have to find one the size of the 7.5hp part number?

looks like:
10hp = 10.6x1.375
7.5hp = 8.6x1.375

You have the correct part number for the motor sheave set. It includes a bushing and pulley. The complete part number description is

SET, SHEAVE 2B8.6X1.375 (8.95X2GR.BXH)

You can buy the parts from IR for $249.

You will also need a new belt, which is CCN 32189284.

The correct compressor speed of the 2545 at 7.5HP is 825 RPM. The compressor sheave size is 18" OD x 17.6" PD, 1 belt, B width. At 825 RPM the compressor will deliver 27 ACFM at 175 PSIG and require 8.2 BHP. If the motor has a 1.15 Service Factor then you're good to go. If the motor has no SF, then go with the smaller pulley (750 RPM).

If you decide to turn the pump at 870 RPM then turn down the maximum pressure to about 150 PSIG so as to not overload the motor.

That pump turning at 825-870 RPM should last nearly forever.

 

[Spyider]

the SF on my new motor i just got today is 1.0..
My plan was to turn it down to the 140-150 psi range no matter what rpm i was gona run at.
so basically what would be best for it, smaller pulley (750) if i want to keep it at 175 psi.
larger pulley (870) but then def turn the psi down to 150..?
The only reason im not going to order the IR parts is because i can get these with bushings for 100$.. ithor size.. thats 150$ saved.. lol.

 

[aptdweller]

If the SF is 1.0, you definitely want to go with the smaller pulley. The pressure setting will change the run time of the compressor, not the power required.

 

[Spyider]

Ok. Thanks for all the help. Ill go with the smaller wheel, and lower the pressure to the 140-150psi range. I dont see a point of going any higher really..
Now i just have to figure out how to get this all wired up with the magnetic starter.. Or just pay someone that knows exactly what they are doing..

 

[stonesfan68]

If the SF is 1.0, you definitely want to go with the smaller pulley. The pressure setting will change the run time of the compressor, not the power required.

No, this is not the case. If you lower the pressure then the required horsepower goes down roughly 1% BHP for every 2 PSI of pressure drop.

Spyider, go with the smaller pulley. This compressor will give you loads of air for a home shop, and last for a long time.

 

[redmondjp]

If the SF is 1.0, you definitely want to go with the smaller pulley. The pressure setting will change the run time of the compressor, not the power required.

Absolutely not true. The higher the pressure, the more power it requires to operate the pump. Turning down the maximum pressure will lower the maximum horsepower required.

Monitor the motor amps as the compressor builds pressure and you will see that this is the case.

 

[Spyider]

ordered the smaller wheel with a QD bushing. i also adjusted the pressures on the switch today.. ON-115 OFF-145.. can always adjust it later once i get this up and running.. i adjusted the pressures with a compressor i'm using from someone else to fill my tank lol.

Gona have my electrician stop by this week some time to let me know what else i may still need to buy to get it up and running.

Q- if my motor has the red button reset on it.. does that mean i don't need the thermal overload strips in my magnetic starter? because it would be like double protected basically.
Also are compressor safety disconnect's required even if my braker box is literally only 20 ft away..? not like ide ever turn it off from their, theirs the switch on the compressor ide use first..