How many time have you wondered if you would have enough propane for your grill to finish tonight's meal?
Here's a tip: At the end of a session at the grill, feel the side of the tank. It will be cooler near the bottom. The spot where it switches from cool to warm is the approximate level of the Liquid Propane. Next time you go to use it, you'll know about how much "gas" you have left.
Can't remember from one grilling session to the next where the level was? No problem, grill out more! Or, do the same trick at the end of your preheat time. That 5-10 mins will cause enough temperature difference to get an idea of the level, but not as much as at the end of the cooking time.
Need a better indicator? pour a cup of boiling water over the tank while the grill is burning. This will cause the tank to get hot and the temperature differential will cause condensation near the level line.
Or you could get one of these guys (this one from Lee Valley:)
But it works exactly the same way, right down to the hot water.
WHY does this work? Go ask your Dad (or Yahoo Answers.)