Quote Originally Posted by Lonesome7.3 View Post
Whenever I fill a 55 gallon drum I will pump it into my dirty tank. That might happen every couple of months. I am interested in your set up. Would you happen to have any photographs?
Sorry no photos. Just duplicated the tranny oil exchange system they use in the quick lube joints except I used stronger tanks that could take a slight vacuum and low pressure.

For your uses, check with your local propane distributor. They always have "stale dated" tanks of all sizes. The tanks are not necessarily bad, just beyond their useful life as pressure tanks.

Remove the brass valve from the top and then fill the tank with water. This is for assurance it won't go bang when you start drilling into it. Would tend to ruin your whole day. A 100 lb tank should hold close to your 55 gallon drum of oil.

In the bottom of your tank, drill out a hole sized to thread in a 3/4 inch NPT fitting that you will attach a ball valve to. Where you removed the valve from, you want to install a brass tee and two smaller ball valves. One will have an air fitting on it and the other will have a vacuum fitting (steal one from the AC system on your car).

To drain your 55 gal drum, connect a hose to your bottom fitting and open the ball valve. Start your vacuum pump and connect it to the AC fitting on the top and open the valve. This puts you into suck mode and will drain your 55 gal drum surprisingly quickly. Let it suck some air in at the end to drain your hose then close off your bottom valve. Close your vacuum valve. To transfer the oil into your other tank just apply air pressure to the other top valve, insert your hose into the other tank and open both top and bottom valves.

Again, less then $200 bucks including a HF vacuum pump and all the valves.

Some safety considerations:

1. Propane tanks are rated for 150 PSI working pressure so the burst pressure is about 3 times that, WHEN THEY ARE NEW. To be safe, keep it under 30 PSI.

2. I have taken a propane tank down to 29 inches of vacuum (negative 1 atmosphere about minus 15 PSI) but that was on a new tank. Pressure vessels are just that, designed to handle positive pressure, not necessarily vacuum. A good example is your typical 55 gal drum. They have a burst pressure of around 40 PSI. Less then 10 inches of vacuum (negative 7 PSI) will crush them flat. To be safe, I would keep the vacuum below about 15 inches for your propane tank.

You really don't need a lot of either pressure or vacuum to move liquid unless there is a significant height difference. Even then you would be surprised just how little of each is needed.

Hope this helps

Bill