We need a pump/compressor to pump gas from one tank into another for changeovers. Any ideas where we can get one?

You have several problems and even though you think you want a lp pump, you don't really want one. The first problem is that lp pumps are VERY expensive. The second is that portable tanks like the 100 lb tanks ONLY let vapor out of the tank since the liquid is heavier than the vapor. What you really need is a auto switch over regulator. You can hook two tanks to the regulator, open both tank valves, and set the regulator us use one tank. Once that tank is empty, it switches over to the other tank allowing you to swap out of refill the empty tank. It is possible to transfer lp from one tank to another. The one to be emptied has to be inverted so that the liquid can reach the valve. Then the tanks are connected together with POL fittings. When the vapor release valve is opened on the tank to be filled, the vapor pressure in the inverted tank will force the liquid lp into the upright tank. Caution, this may be illegal in some jurisdictions and is dangerous everywhere.

Northern Tool & Equipment carries a variety a transfer pumps for diesel, gasoline, hydraulic oil, etc. in a choice of hand, 12 volt, or 120 volt power. Check their website northerntool.com

This type of pump is called a 'recovery machine' when dealing with refrigerants. I'm not familiar with LP pumps that perform the same function.

If would be much safer to connect the tanks together. That way they will both drain. That's not a plumbing job a layman should attempt.

I'd just like to mention the tanks are for an lpg supply to a house, not a vehicle tank.

LPG requires very special kit.

Talk to an LPG specialist.

Something simple like this? There is no simple pump. Just ask the people that deliver your tanks.

http://lp-gasequipment.com/docs/Propane_Air%20Syst...

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