All fire extinguishers should have A, B, C or D classification ratings on them. Class A fire extinguishers douse ordinary paper, wood, cardboard and plastic fires; Class B fire extinguishers douse liquid fires; Class C extinguishers douse electrical fires; Class D extinguishers douse chemical fires. For recreational and household use, a multipurpose ABC fire extinguisher should be used. ABC fire extinguishers may be stored outside as long as the proper precautions are taken to maintain the extinguisher.
If the tank is stored outdoors, brackets may be used to keep the tank off of the ground and out of the way, preventing unnecessary wear and corrosion of the tank.
Whether stored indoors or outdoors, extinguishers should be stored in the upright position to avoid clogging the valve due to the dry chemical settling in the bottom of the tank. To prevent "packing" of the chemical agent inside of a fire extinguisher, shake the extinguisher occasionally.
It is important to keep extinguishers away from moisture build up, because this may cause oxidation and failure of parts. Also, "caking," or lumping, of the chemical agent found in the extinguisher will occur if moisture finds its way into the tank.
It is always important to properly maintain and inspect ABC fire extinguishers. Key checkpoints include tank pressure, signs of corrosion or oxidation, and operation of key parts.
Temperature does not affect ABC fire extinguishers, because they use a dry chemical agent that will not freeze, melt, expand or contract in extreme temperatures.
One major common misconception about ABC extinguishers is that moisture will find its way into the tank if it is stored outside. This is true only if the extinguisher has not been properly maintained.