Connecting multiple propane tanks

RobA · Sep 25, 2015

I just purchased a 500 gallon propane tank to replace the two 120 gallon tanks that my old supplier owns. If I were able to buy those tanks from the supplier at a cheap price is there any reason all 3 tanks couldn't be hooked together to increase my capacity?

Bladehauler · Sep 25, 2015

I'm running 2 250 gallon tanks plumbed together after the regulators. Propane company said no problem as long as I use flare fittings and NOT compression style fittings.

docone · Sep 25, 2015

Check your local plumbing gas codes, if your old tanks were manifolded together, it shouldnt be a problem, as long as it complies with the codes.

RobA · Sep 25, 2015

Thanks. Yes, the old tanks were hooked together. Wasn't sure if 3 tanks of different sizes would matter.

Raspy · Sep 25, 2015

They are all running at the same pressure, so it doesn't matter if there are two or three. But you might just turn on one at a time to keep track of the use. Either way.

drizler · Sep 25, 2015

They make those multiple tank auto switching manifolds and they are old school but work fine. Just wait till the valve has flipped then you know the other one is empty and go fill it. I use one of those 30 buck hand trucks to move my 100 lb 20 gallon tanks to the truck. An old seat belt works nice wrapped around to keep it in place better on the dolly.

bigtiller · Sep 25, 2015

RobA said:
I just purchased a 500 gallon propane tank to replace the two 120 gallon tanks that my old supplier owns. If I were able to buy those tanks from the supplier at a cheap price is there any reason all 3 tanks couldn't be hooked together to increase my capacity?

I wouldn't do it because if all 3 valves are left open, the propane will settle into the lowest tank. That could create withdrawal and/or expansion problems.

Tractor Seabee · Sep 26, 2015

bigtiller said:
I wouldn't do it because if all 3 valves are left open, the propane will settle into the lowest tank. That could create withdrawal and/or expansion problems.

Think about the thermodynamics involved: all tanks are connected at the vapor outlet, that makes them all the same pressure, only way gas can migrate to one tank it it would have to colder than the others to condense vapor into that tank. If all three are open the vapor draw is equal so as the temp drops due to lowered pressure from demand then all tanks are at the same temperature.

Just my analysis based on years in the refrigeration industry. Some engineer could prove me wrong though.

Ron

bigtiller · Sep 26, 2015

Okay, this is me thinking........Ouch!...... ok, i have to do some backing up, Seabee has it correct. I was thinking of an instance in my past that had a liquid withdrawal from 5 tanks to a really big oven. In that case, the gas would travel during filling if a sequence of events didn't happen in the correct order.