Using water to extinguish fire, that is what we generally think of when we encounter fire. But for some types of fire, do not use water to extinguish fire. Because it will spread the fire and even lead to explosion. Below is the fire types which are not allowed to use water for fire extinguishing.
Water is electrical conductive material, if use water to extinguish electrical fire, it will cause electric shock and may lead to person death.
So, for electrical fire, we should firstly cut off the power supply. Then use carbon dioxide extinguisher or wet quilt to extinguish the fire. Foam extinguisher is not allowed for electrical fire extinguishing cause it is conductive material as well. If the hot fired TV set or PC etc. electrical appliance meets the water, it will explode.
If fire happens on oil pan, do not use water to extinguish fire! The hot fired oil will spread with fire when it meets water. So, the fire will spread suddenly. Immediately cover the fired oil pan with cover or throw wet towel, vegetables into fired oil pan to cover the fire.
The density of fuel oil such as gasoline and paint is smaller than water, when use water to extinguish it, the water will sink and oil or paint will rise, then the fire spread. So, do not use water to extinguish fuel oil or paint fire. The correct way is using dry powder extinguisher or sand to extinguish the fire.
Most chemical substances will have a chemical flame reaction when they meet water. The substances include sulfuric acid, nitric acid, hydrochloric acid, metal potassium, sodium, aluminum, magnesium etc.
Do not use water to extinguish gas fire! The flammable gas such as coal gas, LPG, natural gas can not dissolve in water. They are lighter than water and can not be covered by water. So, if use water to extinguish the gas fire, the fire will spread. The correct way is using wet towel or wet quilt to cover the fire. Then, quickly close the gas valve.