HVLP Painting Question

A HVLP-painting question was submitted to this compressed air site.Thanks to Marc from Chestertwon MD for his question about compressed air flow and HVLP. Hopefully the answer will help others.

Mark's Question was I recently bought an old compressor with a leaking tank at an auction. The motor and pump are good, but they do not indicate horsepower.

If I purchase a large enough tank, would I be able to run an HVLP gun even though the motor was not rated for the scfm on the gun? I would run the gun off of the air in the tank and then take a break when the pressure gets low.

I am assuming I will have to purchase a high quality filter as the pump would have to run for a while to fill up the tank, building up a good deal of condensation.

Also, I have seen propane tanks converted to serve as compressor reservoirs. What is involved in this, and are these tanks usable for painting applications?"

My Response Hi Marc, thanks for the question.

Regarding your High Volume Low Pressure paint gun, these units come with a turbine to provide the high volume. Some of these turbines produce 100 CFM at 3-5 PSI for the HVLP guns.

How large a tank will you need for it to produce the flow necessary? I suspect that you'd draw down the receiver very quickly, and you would have to wait for the compressor to re-charge the tank before using the gun again unless the pump can produce more air than the paint gun demands.

I don't know the HP of the motor on this compressor. I am surprised there is no information plate on the motor. Perhaps there is, and it's on the inside of the motor wiring hatch? If you could figure out the HP of the motor, you can guestimate that you'll get 3 or 4 CFM of compressed air from the pump at 90 PSI for each HP of motor your compressor has.

If you have the tank, already have the gun, and a 40 micron air filter, 5 micron air filter downstream of that, and maybe even a desiccant in-line dryer before the gun, give it a try. If it provides the flow, then you're golden.

I, too, have seen propane tanks converted into air pigs.

Is a propane tank cheaper than an air pig / tank at your local industrial supplier? You will know that if you buy an air pig that it will be rated for compressed air use. Unless the propane tank is certified for compressed air use, indicated by a stamping on the tank itself, I would not use it.