Compressor Pump Conversion

[noggenfogger]

I need to modify a piston pump to pump air instead of oil. The pump is capable of compressing the gas however the oil was also the pistons lubricant. How could i modify this pump to lubricate itself? I was thinking of placing a small tank of piston oil on the inlet pipe so it lubes that way. However, it would continue to drip in when the pump is not working. Any help is much appreciated.

 

[JJPellin]

There are commonly available in-line oilers that should work. The oilers are designed to introduce a very small amount of oil into an air line running to an air tool or air motor. They only add oil when there is a flow of air. Take a small line from the discharge side of the compressor. Orifice the flow to match the flow requirements of the oiler. Take the outlet of the oiler and pipe it into the suction side of the compressor. When the compressor runs, oil will be added to the stream. When the compressor stops, there will be no flow so no oil will be added. You will loose some of your air flow from the output of the compressor. But, depending on the size of the compressor, this may be insignificant.

Johnny Pellin

 

[MikeHalloran]

Be careful, though. If you're expecting a discharge pressure much above 200 psi, the pump may confuse itself with a Diesel engine and initiate a combustion event that will destroy the pump. ... not to mention the collateral damage.



Mike Halloran
Pembroke Pines, FL, USA

 

[Compositepro]

An oil pump is likely to perform very poorly as an air compressor. A pump designed for incompressible fluids does not have to be designed to have a low non-swept volume between the piston and valves. Air in this volume will simply compress and re-expand without being swept out past the exhaust valve.

 

[hydtools]

What sort of piston pump?
Can you put some quantity of oil in the case and get enough splash lube for the pistons? Ususally a piston pump has a case that collects piston leakage and returns it to tank via the case drain.
Lube the mechanical side and not the air side.

Ted

 

[micalbrch]

As Mike Halloran wrote - be careful. A piston pump is a piston pump and not a compressor. Compressing gas creates heat and the higher the pressure the more heat is created. Stopping the oil flow to the pump's pistons is the smallest problem to solve. Install a solenoid valve in the lubrication line. Pump works - valve is open. Pump is stopped - valve is closed. But I would take exception from this job. It is too risky.