I did a search and could not really get an answer of what i wanted and it made me think of some new questions. Since soap could damage some parts of a fire engine could it hurt any part of a fire extinguisher?? How much soap should be added to the 2 1/2 gallon extinguisher?? How can you keep a H2O extinguisher from freezing when stored in your POV during the winter. Temps usually dont get below 0. Thought of antifreeze but thought it was flammable?? Any suggestions? Thanks.