Under unusual conditions, propane may be mixed with air and used as a substitute for natural gas (propane shaving). What is the composition of a propane–air mixture to obtain a HHV equivalent to...

Under unusual conditions, propane may be mixed with air and used as a substitute for natural gas (propane shaving). What is the composition of a propane–air mixture to obtain a HHV equivalent to methane? Is the mixture safe? Methane and propane have HHV of 1010 and 2516.1 Btu/scf (37.706 and 93.934 MJ/Sm3 ), respectively; the flammability limits of propane are 2.0–9.5vol%