I don't think 144a is propane based as it is very similar in power to 134a which is a non flammable Tetrafluoroethane. Again, 144a from my understanding only exists in the airsoft world and is a creation by Abbey to replace 134a and is named purely for the similarity to 134a not down to which carbons the the fluorine atoms are on like 1,1,1,2-Tetrafluoroethane.