Can someone school me on how to use a manometer for propane?

[sclifrickson]

Originally Posted by Brian B-P

Yes, that makes sense, as long as the regulator effectively checks any backflow (so it doesn't lose propane out of the inlets, which would look like a leak. It definitely shouldn't allow propane out of the inlet from the secondary tank, but I don't know about the primary. So maybe unscrew the hoses, then put them back on (leaving the tank valves closed)?

I would wager that the regulator has some sort of backflow preventer as otherwise every time you unhooked tanks you’d get 11 inches of water worth of propane shooting back at you, right? I’d think that would be noticeable. There’s always a small bit, of course, but I’ve always just thought that was the residual in the high pressure lines from the tank to regulator. I suppose someone with a manometer could answer all of these speculations...

[Brian B-P]

Originally Posted by sclifrickson

I would wager that the regulator has some sort of backflow preventer as otherwise every time you unhooked tanks you’d get 11 inches of water worth of propane shooting back at you, right? I’d think that would be noticeable. There’s always a small bit, of course, but I’ve always just thought that was the residual in the high pressure lines from the tank to regulator.

With most automatic changeover regulators, only the secondary tank is supposed to be changed - it's assumed that you're running on the primary. If you remove both, they're likely both empty, and it's really hard to detect any flow from a hose with only low-pressure propane in it; the high-pressure propane in the tank hose is what you notice coming out when changing tanks, since there's no check valve in the hose end fitting. So yes, both sides of the regulator input should have check valves, but perfectly working check valves on both - I don't know.