As the name implies water-based fire protection systems use water as a primary means for fire protection or suppression or extinguishment. Water is cheaper and available than any other fire extinguisher media and has a higher heat-absorbing capacity. Therefore it is extensively used around the world.
Water is used for extinguishment of class A type of fire. Class A type of fire includes all solid common combustible materials we use in our daily activities such as wood, paper, clothing, etc
Why water is popular for fire fighting
It’s cheap
It’s available
It’s non-toxic
It’s efficient
How does water extinguish a fire
By cooling
Water has high specific heat ( 4.2 kJ) and latent heat of vaporization (2,260 kJ) hence it can absorb a huge amount of heat energy (around 3 MJ/kg ) during changing its phase from liquid to heated steam. The impingement of water on the solid fuel surface reduces the rate of pyrolysis by the cooling of the surface thus reduces the heat release rate. As fewer material burns, the flame size is reduced and the thermal feedback to the fuel is reduced. This further reduces the production of heat and the cycle continues until fire extinguishes.
By displacing oxygen
Water vaporizes when it comes in contact with fire. The volume of water vapor is 1,700 times greater than liquid water at 100°C (212 °F) and at 600 °C (1,112 °F) it expands over 3,980 times. This vapor displaces the oxygen in the fire compartment area, its flammability range shrinks. At a certain point, the mixture will no longer be flammable and therefore rendered inert and the fire dies out.
Water-Based Fire Protection Systems are
- Standpipe and hose system
- Fire Sprinkler system
- Water spray fixed system
- Water mist system
Foam based fire protection systems are also heavily relied on water supply as 94% to 97% of foam is water.