Free air compressor and snow blower

[old_nodaker]

Compressor is from the school where I work. It was removed from service about 12 years ago and been sitting in the way ever since. No one wanted it cause it has a 3 phase motor on it, plus lots of hours. Heating system is controlled by air pressure, so it ran 50 percent of x number of years.

The snowblower was from neighbors of the school. The auger and drive don't work and the tires are flat, but the motor started right up.

I will be hooking up the compressor to see if it's any good, but my ultimate plan was to put the motor from the snowblower onto it. But....I got to wondering, how would that work? What happens when the compressor is up to pressure? Is it only controlled by shutting off the motor or does it have the ability to just go off line while the engine keeps running? I don't have a huge need for this setup so if it's not relatively easy (cheap) to do I'll give up on it.

[macdaddy]

Wish there was a way to ship that snow blower reasonably.

[Mark / Ohio]

Nice find old_nodaker! :thThumbsU

You could put a relief valve on the tank to bleed the excess pressure. Similar to a pop valve but more even regulation I think. McMaster-Carr carries them. Not real cheap but much cheaper than a new gas compressor.

http://www.mcmaster.com/

[professor]

There is always a relief valve somewhere on the unit. You could also use a hot water tank relief.

Mike

[cleatusj]

If you used an electric pto, it could be hooked to the preasure switch to dis-engauge.

[jodyand]

I don't know how it works but all the gas powered air compressors i have seen the motor goes to an idle when the pressure is reached. Then back to WOT when the pressure goes down to the point set for it to come back on.

[old_nodaker]

It does have a pressure relief valve, but seems like that could be dangerous. Trucks with air have compressors that just stop pumping when they reach pressure, but I think it's built into the valve mechanism, not something that can be added on. The electric clutch idea would work, but I don't have one kicking around and the project isn't worth that kind of money. I'm quickly beginning to think it's not a practical idea. Maybe the engine will go toward a vaccum!

[RoGT5k]

What about fixing and selling the snowblower and using some of the money to buy a single phase motor for the air compressor? The snowblower looks pretty nice and you are approaching a good time for selling one with winter coming. Just my 2 cents worth.
Roger

[Ingersoll444]

I don't know how it works but all the gas powered air compressors i have seen the motor goes to an idle when the pressure is reached. Then back to WOT when the pressure goes down to the point set for it to come back on.

Jody's right. It uses a pressure switch that dropps the motor to idel. A simple setup realy. Now one thing. If I am not mastaken, the motor turns the other way. So you would need to swap the pump to the other side, and put the motor where the pump was. At least thats the setup everyone I have seen has been.

If you need more ideas, I have a buddy with a gas powerd compressure and maybe I can get him to snap a pic or two of the setup.

[mla2ofus]

That pressure switch also dumps air off while engine is idling,then closes when switch speeds engine up.
Unless you need it outdoors a lot, I would go the elec motor route. How many HP is the 3 ph motor?You will probably need a little more HP w/ a single phase motor.A capacitor start motor may have as much staring torque as the 3 ph. Maybe one of our electricians will see this thread and be able to tell you.
Mike

[old_nodaker]

Thanks for the ideas. As I said in the beginning, This isn't something I really need, I already have a electric one. Probably the best idea would be Rogers, fix the blower and sell it, then fix the compressor and sell it, then go buy a vaccum. But what fun would that be?

FYI - It does rotate the same as the gas engine runs. The electric motor is 3/4 horse, but I suspect this was setup to only go up to 60 lbs pressure (rather specialized application) so maybe was a smaller motor then normal.

[slipshod]

At any rate you made a good score!

[RoGT5k]

...... But what fun would that be?......
Oh, I get it, you're looking for a project. Ok, so what we want to do is have the engine disengage it's drive and idle down when the tank reaches adequate pressure. I think you can accomplish this with a centrifugal clutch and a 110v solenoid. There should be a pressure switch on the compressor that turns on the motor when the pressure drops beyond a certain point. If you were to use that pressure switch to power the solenoid, the solenoid could be used to control the engine's throttle. When the pressure reaches the present high limit, the pressure switch will cut power to the solenoid and thereby reduce the engine speed to idle. As the engine rpm's reduce, the centrifugal clutch will disengage the drive and the allow the engine to idle without driving the compressor. If any of this were to fail, ie. springs break in clutch or solenoid jam, the pressure relief valve that should already be in the compressor system should be able to dump the pressure. I believe I have seen centrifugal clutches with vee belt pulleys on them before. :goodl:
Roger

[saselker]

not an expert by any means but the larger commercial compressors I've seen usually run continously(electric motor), there is an air operated mechanism to control the valves when there is demand for air. Shops that have a lighter demand for air set them up to shut off the AC motor when up to pressure(saves a little $$ on electric bill), but the valve control is still used to allow the motor and compressor to come up to speed before actually pumping. I had a setup like this at a shop I worked at, it ran in continous mode for like 25 years untill it was moved inside and changed over to "intermittant". The old thing didn't last long after that.
Maybe the unit you have has a similar setup, look for small lines going to the head(s).

[johndeere]

Just make sure you check that tank real good for pin holes rust spots.Thats why many including mine are taken out of service.Dont want to see you have to pick shrap metal out of your face from a rusted air compressor.

[old_nodaker]

Saselker - that would sound like a setup similar to what trucks with air compressors must have, they run constanly, but have a unloader valve for when they're up to pressure.

Anyway, my shop compressor has given up the ghost, so I'm just using this one now as is for shop use. Thanks for all the ideas.

[mbkerk]

I missed this thread last year.

OND... Northern sells just what you need. A non-powered device that unloads the compressor and sets the engine to idle when pressure is reached. When the low limit is reached, engine speeds up and unloader valve closes! Really slick way to do this. Compressor is not altered in any way, air just goes to the atmosphere instead of into the tank when unloaded.

I am going to build one of these sometime this summer.

[Kbeitz]

A cheap way is to put a 12 volt air compressor clutch (off a car) on your engine with a pressure switch that has the little air tire valve hooked on its side... The pressure switch would disengage the clutch and also let the air off the head ...