Propane Auto Switch Over Valve

[illapah]

Bill and Paat - I posted this in another thread. Hope it helps

From April 08 issue of Highways magazine, page 30:
Editing the article start - Both tanks full and open, selection lever pointing to left cylinder. Red/green indicator is green. Stove burner lit to verify gas supply. End edit.

Here's where the meat of the test starts. We had him close the left cylinder valve, which simulates running out of gas in this cylinder. The indicator turned red. He then looked at the burner flame; it was still burning, which indicates that the regulator had switched to the right cylinder automatically. We then had Rich switch the lever to designate the right cylinder, which made the indicator go green. While these regulators are described as "automatic", the owner still has to physically move the lever to the designated cylinder to make the indicator go green again. Once that indicator is green , it's OK to remove the empty cylinder and have it refilled.
We then asked him to open the left cylinder valve and close the right cylinder valve, repeating the previous test, only switching cylinders. He experienced the same results and proper function.
After the tests, we had Rich open the stove burner while the cylinder valves were closed, bleeding off the propane and causing the indicator on the regulator to turn red. Rich carefully opened the service valve on the designated cylinder to slowly introduce enough gas to;make the indicator go half green (you really have to be quick enough to do this). We wanted to show him that the red/green indicator is actually a pressure guage and that it could also be used to perform a pressure-drop leak test - because there was enough pressure in the system to make the indicator show some green. As long as the system does not have a leak, it will continue to show green. If the red/green indicator does not drop to red after a few minutes, that indicates there is no substantial leak (theoretically nothing is absolutely leak free, and standard for this test is a minimum of three minutes).
Then we asked Rich to open the stove burner for a few seconds to simulate a leak, and, sure enough, the indicator turned red.
These tests showed that gas did flow from each cylinder and the automatic-switchover regulator functioned as expected. The propane piping system also passed our leak test.
Many, if not most RVers don't actually know how to use the automatic-switchover regulator to its maximum benefit. These regulators allow the owner to leak-test the system, provide continuous appliance service after the designated cylinder runs out of gas (as long as both cylinder valves are left open), and the system actually functions as a fuel-level guage because it shows you when to refill the empty cylinder. END OF ARTICLE.