Since I am the resident jack of all trades at work, I have been assigned to go to farms and gather used engine/hydraulic oil for burning in our waste oil furnaces. In the past I have used a centrifugal pump to suck oil out of barrels or storage tanks. I pump the oil into a 1000 gallon pressure vessel formerly used to transport anhydrous ammonia.

Pumping thick used oil at cold temperatures is difficult and slow. I decided to try speeding things up a little by putting vacuum in the pressure vessel, thinking it would make priming the centrifugal pump much easier and would assist the pump in moving the oil into the vessel. The pump has a 5hp OHV Briggs engine and when it is pumping correctly it pulls the engine VERY hard.

The input shaft seal now leaks on the centrifugal pump, probably due to me putting too much vacuum in the vessel attemting to suck oil into the pump to prime it while the pump engine was running. After some experimentation I was able to use the vacuum pump by itself to get the used oil into the vessel, although I did get the vacuum pump pretty warm once by not allowing some air to flow through the pump to keep it cool.

My vacuum pump is a Gast 4240-V2, which according to specs is capable of 20" Hg and 40 CFM. It came out of my Grandps's milk barn after he quit milking cows in the 70's. It is a belt-drive pump that I am powering with 5 hp Tecumseh OHV engine. I would guess that I want to run as much vacuum as possible (18"Hg+?) but allow enough air through the pump when the vacuum level is reached to keep the pump cool. I would like to make this oil-gathering operation as foolproof as possible because I am not always going to be the person gathering oil and it need to be pretty much idiot-proof.

Can anyone get me headed in the right direction with regards to a vacuum regulator? If there are any other concerns I need to be aware of, please speak up!

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1951 Chevy 1/2-ton Pickup truck