No clue yet, but your average grill regulator goes to ~5-10psi...mine goes to 60psi :fuckyeah: The knob on the tank was open about 1/4 turn for the photos above. I turned it to about 3/4 turn the the flame was ~3ft high. Keep in mind the regulator was set fairly low...
Edit: According to the Moore County Boy Scouts of North Carolina...
"The average full-size gas grill goes through about 1 pound of propane for every 30 minutes of cooking time. But how many of us cook with a stopwatch? There are a few simple ways of determining how much propane is left in the tank.
A normal-size 20-pound capacity tank weighs 17 to 18 pounds empty, and 34 to 35 pounds after being filled. To determine how much gas is left, weigh the tank and subtract 18 pounds for the tank; multiply this number by 30 to determine approximately how many minutes of grilling time are left.
(weigh the tank -- 18 * 30 = minutes of grilling time are left)
Pour hot water over a section of your o o tank, then run your hand up and down ii' the side. The part of the tank that turns warm is empty; the part that feels cool is full. You can get an idea of how much propane is left based on this."
Obviously a fire pit will burn more propane but I found this info interesting.