Which type of fire extinguisher is NOT suitable for class "C" fires?

Class "C" fires involve flammable gases, such as propane or methane. When addressing these types of fires, it is critical to use extinguishing agents that will not conduct electricity or react with the burning gas. The water extinguisher is not suitable for class "C" fires because water can conduct electricity and may cause further hazards, such as electric shock if the equipment involved is live. Additionally, using water could potentially spread the flammable gas or create a more significant fire risk.

In contrast, CO2 extinguishers and dry powder extinguishers are effective for class "C" fires because they do not conduct electricity and are specifically designed to displace oxygen, interrupting the fire's chemical reaction. Foam extinguishers, while primarily suitable for class "B" fires, should not be used on gas fires since they may not effectively control or suppress them in every situation. Therefore, selecting an appropriate extinguisher is crucial for safety and effective fire response, reinforcing why the water extinguisher is deemed unsuitable for class "C" fires.