I need some air

[Tom]

On of this summers projects is to add a compressor to the 6/1 so it can be used to make compressed air for sandblasting and painting projects. The plan is for air or generator, and not both at the same time. Creating as much CFM as possible, given the available HP, will mean I need a good match between the compressor. There is a 12" double B groove pulley on the engine crank shaft that came with it.

I've been exploring 2 routes to accomplish this goal, one is to buy a HF compressor http://www.harborfreight.com/air-tools/compressor-pumps/145-psi-5-hp-twin-cylinder-air-compressor-pump-67698.html and run the "V" belts on the flywheel. This compressor is for a 5hp electric motor, so I don't know how well a Listeroid 6/1 will power it. Another way to go seems to be to get a used air brake compressor from a diesel truck. An advantage to the truck unit is that the pressure regulator is already there.

And this leads to another question, with the HF compressor, how would the compressor be disconnected when the pressure set point is reached?

Tom

[honda lee]

Hi, I would think you could just use a pressure relief valve set to relief where you set it and auto reset. Like those used on well pumps.
Lee

[carlb23]

You can use an Air Compressor unloader valve commonly used on gas powered compressors.  Some of the unloaders have a cable that can idle the engine down when unloaded.  You can find them from around 40 dollars or so on ebay.

[BruceM]

I use the 3 cylinder Eaton 2 stage pump on my 6/1, running at derated speed. Only a single B belt is needed, I could have saved some money on the 20" pulley.  I've got enough power to pull 1000 watts on my ST-3 in addition.  I was impressed with the support I got from Eaton, both before and after sale.

 http://www.eatoncompressor.com

I also use an air relief valve for control; the Eaton pump has pneumatic unloader valves on each cylinder which hold the inlet air valves open.  I also use the unloader valves to "deselect" the compressor when I'm using the generator and have both belted.  It still has a fair amount of drag so I unbelt it when I'm not using it for a while.

Here's a pneumatic control valve like the one I use:
http://www.compressor-source.com/Air_compressor_pilot_valve_125_150_psi_p/rcb-m-hu125-150.htm

The Harbor Freight unit wouldn't keep up with an air sander.  It's rated for 15 cfm at 90 psi. You need about 4 times the rated CFM for the tool - so say at least 24 CFM at 90 psi for a sander. Air tools' stated CFM are rated at 25% duty cycle, so don't get fooled about their real air needs.  That will take a larger 2 stage pump that a 6/1 can't handle.  So then you must have a large tank to meet the demand, while the compressor slowly plays catch up.  My air tank is 500 gallon.  

I don't see a pulley size for the HF unit.  I know B belts aren't designed to run on a flat pulley but I'd try it if the speed reduction worked out right.  My Eaton compressor would be over the rated speed with it's stock pulley/fan with my engine at 650 rpm, so I had to buy a big pulley for the Lister. Very expensive.

Best Wishes,
Bruce

[mike90045]

Do you have 240VAC from the inverter ?
 Why not a mains powered compressor, and in summer, it's free power, 'cause I know your 'roid is not "portable"

[Tom]

The pump pulley is 14.5 so a 23.5" flywheel at 650 rpm would run the compressor at 1053 rpm, just a tad over the max rated speed of 1050. The specs of the Eaton pumps are right in there with the HF one being in between the 3 cylinder 1 stage 18 cfm and 2 cylinder 32 cfm 2 stage. The 3 cylinder 2 stage pump seems to take a lot of hp, are you sure that's the one you're running Bruce? Wow a 500 gal tank is huge. I have a 20 gal propane tank I was thinking of using, guess I should look for something bigger. Thanks for the info!

Mike, I plan on doing some vehicle painting that will require all day use of the compressor running sanders. Running a 5hp compressor is a big the hit on the solar system, it would be more than the panels put out at max and the bats would run down quite a bit after a day of work. Besides the listeroid needs something to do during the summer time.

[mike90045]

Run the listeroid to charge, or have the inverters provide generator support.

 Why compressed air sanders, do they last longer than electric orbital sanders >