Powder Extinguishers are used for Class C fires. Class C fires are flammable gases, propane, butane, methane etc. This extinguisher works by forming a barrier between the fuel and source of oxygen which interrupts the chemical reaction taking place.
Powder Extinguishers should not be purchased if they are intended to be used indoors unless mitigated by a Health and Safety Risk Assessment. In small confines this could cause a sudden reduction in visibility and could impair breathing which could jeopardise escape for the person attempting to extinguish the fire.