Originally Posted by Joe Z
I had a set of 30 pound tanks about five years ago with the newer OPD system and it had a gauge in it but the gauge had it's own separate hole in the tank and the gauge had a float of it's own that measured the liguid level inside (not pressure)......... that thing worked perfect for me. I do agree the pressure ones do give some degree of reliability.
I also have a set of two 30 lb. tanks with the new OPD system and mechanical gauge for each tank. These gauges indeed measure LPG levels. Pressure gauges are great to measure pressure; if you have pressure you have LPG, no pressure - no LPG, kind of binary gauge. With a mechanical level gauge I can anticipate if refill is needed ahead of running close to an empty tank.