I have a standard hand-held Benzomatic propane torch, probably 35+ years old. Fortunately I have never run out of gas in the middle of an important project, and I do have 3 hardware stores within a five minute drive. But I sometimes do projects late at nite after the stores would be closed, and it would be nice to know when my propane cylinder (~2.75" diameter, 11" long)is about to run out.
I could weigh an empty cylinder, but that could be tomorrow or late next year, I don't have a clue how much my present cylinder has been used. Ideas ???