I've noticed that certain propane torches will have a seemingly linear relationship between their PSI and BTU/hr. IE, 18 PSI -> 220,000 BTU/hr. From this a person could calculate how much gas is being burned per sec/minute/hr. So, is there a general relationship/formula that I can use to calculate gas flow rate based off the PSI? Like if I have a propane tank releasing propane at a pressure of 25 PSI, how could I calculate how much weight in propane is being burned per second (without knowing the ratios in the first paragraph)?