What Im wondering about is the difference between old style and new style. The old style are heavy monsters that do not use capacitor start. The new ones are much smaller and use capacitor start. Which has more torque, especially at startup? So the question is: I have an old style Peerless, 3HP, 1750 rpm, 17A at 230VAC. I also have a modern Baldor, 5HP, 1725 rpm, 23A @ 230VAC. Mounting either one is no problem. So which one would you use with a 1963 Curtis pump rated up to a 5Hp motor? And what rpm should that pump be run at? It has a 14" 3 belt flywheel, the 3HP motor has a 2 groove 5 1/2" pulley/sheave. The Baldor is naked. A related question: The 1963 Curtis tank has a coating of rust inside; no real heavy scale and rot pits. How would you go about cleaning it? I was thinking of a molasses treatment which would take about 10 days.
This could be all be determined exactly if you had all the perfomance numbers on the pump. Without the right data yoiu just have to shoot from the hip. I would use the Baldor motor. You should probably buy a new three-belt pully for the motor. I'm guessing the Baldor has a 5/8" shaft. If the older motor had the same size shaft you could swap the pully and give it a try with two belts. The older motor probably has a 3/4" shaft though. I would try a three to 3.5", three belt pully. The best way to find the right size, would be to use and adjustable sheeve and an ampmeter, but you may burn up a belt or two tinkering with it (with only one belt). The motor should run near the FLA (full load amp) rating. Use the tank at you own risk.
The old 3 Hp has a 1" shaft, the Baldor is 1 1/8". There is a Grainger a few towns over so I can get any pulley I need. As far as running Im more concerned about not exceeding the pump rpm ratings. The only marking besides the bore and stroke is that the minimum is 300 rpm. Thanks for the hint on the FLA, I have a 25A AC Ampmeter.
Sometime in the 80s the Fed. govt made laws to save energy. It seems to me that an old 3hp motor is about equal to the new 5 hp motors, hence the cap. start.
Good thread 286..... Not to hijack, but I"m getting ready to do basically the same thing. I bought a large tank off of a fella for $40 and another fella has a compressor and motor that he said he'll give to me......worth a shot... some good info here... what would be the concern over the tank....too thin?
You ever see a tank blow up? I have. It took out all four walls of a 30 by 40 shop, just the corner posts holding up the roof. The tank ended up over 100 ft out in a field. It wrapped a 800 lb freezer around a buddy of mine, breaking his hip and pelvis in several places. I use new tanks only. And change them every few years
286MERC, I have afairly new 5HP Ingersol Rand compressor. Compressor pulley is ~13" OD and the single sheave Baldor motor pulley is ~ 5-1/2". Motor shaft is 1-1/8" OD; speed 1750 rpm. If I did my math correctly the ratio is 2.36:1 so at 1750 rpm motor speed compressor is running around 740 rpm. Hope this helps! Blown49
I just built one to replace my horizontal 30 gallon. A little place about 50 miles north sells factory return tanks so I got an 80 gallon upright. The head is a single stage that puts out 13.5 cfm at 90 psi. The motor is a 5 hp, both from Harbor Freight at $99 each. The check valve, pop-off and cut-off were from Grainger and the two groove pulley on the motor from Bearing Service. I have $400 in it. I painted my Mercedes this winter with an HVLP gun and the old compressor wouldn't keep up any more. Then I tried to sand out the clear and it REALLY wouldn't keep up. The pulleys were sized to make the compressor run at rated RPM when the motor was at its rated rpm. Good luck. There's nothing better than telling people you built your own compressor.
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