The Stovebolt Site Forums The Shop Area General Truck Talk BIG Vacuum pump, need project help

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!

Over in Lincoln is the headquarters for Masport . They build industrial vacuum pumps and vac truck components. You might learn something surfing their site or even call them for some tech help. Or they might refer you to a truck shop/dealer/distributor that could help you. Safety is the most important thing. Does the old anhydrous tank have a data plate that gives the pressure rating? It's probably more than adequate - if its not corroded and thin on the inside, where you can't see. Your 20" Hg rating is approx 10 psi of external pressure trying to implode your tank. Apply that pressure to maybe 18000 square inch inside area and that's 180,000 pounds total force. Be careful!

Carl, you once you have acheived 20"hg of vacuum in the tank, turn the pump off. You will not lose very much vacuum unless you let air into the system. What diameter and length of hose are you using?
Check out my company www.sageoilvac.com. Our units are made for changing oil, but we have customers that use our units for gathering waste oil from farmers. We usually acheive 20"-24"hg of vacuum on our tanks.
Too bad Southwest Implement doesn't pick up the waste oil before it gets cold. Its hard to suck molassis through straw.

Phil

Thanks Phil and Frank for your replies. To answer some questions:

I think the tanks are rated for 300-350 PSI if I recall correctly.

I am currently using 2" hoses with cam-lock fittings. The hoses are 15' long and I use the shortest hose length I can. Most of the time I use two hoses so figure 30'. The vacuum pump uses a 1" hose with 1 1/4" valves and fittings. We have the tanks rigged up with a 2" valve on the top and the bottom of the tank. I use the bottom valve to unload the oil, either by putting air pressure in the tank or using the now defunct pump to pump oil into the heater tanks. I use the top valve to receive oil from the farm. The 'stinger' I stick down in the tanks or barrels just fits inside a 2" bung. My problem with using the pump is that as soon as the pump sees air, it quits pumping and the oil quits moving. This leaves the suction line mostly full of oil and the pressure side completely full of oil. This is a mess at best.

The vacuum works great because it purges ALL the oil from the lines and it is self priming. With the pump I spent a LOT of time getting the pump to prime. I like the 40 cfm that this vacuum pump moves because the rush of air through the lines insures that no oil remains in them. I would like to maintain a continous vacuum in the nurse tank so that when the tank/barrel empties there will be no chance of oil staying in the lines waiting to spill out when I switch barrels, tanks, ect.

We usually begin running the heaters in October and it typically takes from October to December to burn the oil we accumulate over the summer in the shop. Also, during the summer, everyone is too busy doing billable work to gather oil, which is not billable (unless we can convince customers to pay us $64/hr to gather their oil). If it is really cold the water in the barrels is mostly frozen so the water stays on the farm--we can't seem to burn water very well.

If someone has an idea of how to separate the oil from the water I would be interested.