Air tools rant

[orezok]

If you want to determine the true horsepower of a motor, take the running load amps, multiply by voltage to obtain watts. Divide by 746 and you have horsepower.

 

[JB4310]

Is the motor 110v or 220v, mine is a 220v motor that draws I think 16.5 amps, If yours is a 110v motor, it is way over rated, the most you can get from a 110v 15 amp, circut is 1.5 hp.

This is on a 20 amp breaker, it will pop a 15. But that still probably means it well below 5 HP. I think this can be wired either way, 220 or 110. Was thinking of wiring it 220.

If you want to determine the true horsepower of a motor, take the running load amps, multiply by voltage to obtain watts. Divide by 746 and you have horsepower.

Thanks, I'll have to get the calculator out.

JB.

 

[Bird]

JB, I'm no electrician, but I can assure you that you do not have a true 5 hp motor. Back when I bought my Puma "6 hp" 60 gallon compressor at least the salesman told me, "We call it an imitation 6 hp" and then he showed me one of their 80 gallon, 2-stage compressors with a true 5 hp motor. And of course a true 5 hp motor is at least twice the size of yours. My current 30 gallon tank compressor is rated at 7.0 CFM at 40 psi and 5.7 CFM at 90 psi (most air tools run 90 psi). I'm sure it's as big and powerful a motor as yours, but rated at 1.8 "running" hp. It also can be changed to 220 volt, but I've left it on 120 and right on the motor itself, it says it'll pull 15 amps on 120 volt. Of course I've never had the breaker kick off because it's on a 20 amp circuit with the receptacle to which it's connected less than 3' from the breaker panel. And I do sometimes run it continuously for long periods of time.

 

[k0ua]

I have one of those "5 HP" CH oil-less compressor's also, It might pull 5HP for a millisecond on startup or some other convoluted way of figuring Horsepower,
It looks to be about a 1 HP motor to me. And it makes enough racket that Zombies and Vampires come up out of their graves in the middle of the day just to see what all that noise is! It does work though, and I have gotten a lot of use out of it. When it dies, I will get a real air compressor some day.

James K0UA

 

[SPYDERLK]

If you want to determine the true horsepower of a motor, take the running load amps, multiply by voltage to obtain watts. Divide by 746 and you have horsepower.

That would give a very optimistic answer. Divide by 1000 instead of 746 to get a closer answer considering efficiency. This will still be a little optimistic on single phase motors.
larry

 

[Bird]

That would give a very optimistic answer. Divide by 1000 instead of 746 to get a closer answer considering efficiency. This will still be a little optimistic on single phase motors.
larry

You fellows undoubtedly know more about that than I do, but since my motor is labelled at 15 amps X 120 volts divided by 1000 comes up with 1.8 and sure enough that's what it says on the tank and in the manual.

 

[orezok]

That would give a very optimistic answer. Divide by 1000 instead of 746 to get a closer answer considering efficiency. This will still be a little optimistic on single phase motors.
larry

I agree, 746 is the theoretical HP and the one that is legal for advertising. Given friction losses, heat conversion and other parasitic loads, 1000 is probably real world.

 

[Kyle_in_Tex]

Been around machine shops all my life. We usually have scroll or rotary vane models. Although I've seen some IRand duds, we have one at current job that just got rebuilt with a tad over 55,000 hours. the rebuilt scroll alone was over $7000 installed. This is a 30 hp model. Run it at 125 psi.

My all time favorite is Kaeser. We had 2, 25 hp models at one shop, each with over 25,000 hours and almost never had any problems.

Another favorite is Hydrovane. Although these run at a lower 105 psi setting. I think we had 32,000 hours on the one we bought used at an auction.

Quincy builds good stuff as well as others. You just have to ante up to get into this arena. It all can be worked out into a cost per cfm at your needed psi dollar figure. If you don't need much air, you don't need one of these.

PS, I come home to a small little "buzz" model that annoys the H outta me.:laughing:

I have an oldie but goodie 5hp 3 phase speedaire but no 3 phase here at the house.

 

[deereman75]

It might be worth it to either get a phase converter for the compressor, or put on a single phase 5 horse motor.

 

[Kyle_in_Tex]

It might be worth it to either get a phase converter for the compressor, or put on a single phase 5 horse motor.

A good 5hp single phase motor is $500 or more! Unless I can find a good used motor, I'm not needing that much air.