Soda-acid fire extinguishers comprises of sodium bicarbonate and sulphuric acid. It is the most efficient house-hold fire extinguisher. It consists of a strong iron vessel with a side discharge nozzle. The iron vessel is filled with a sodium bicarbonate solution.
The working principle of any fire extinguisher is based on the following three conditions:
- cooling of the combustible material below its ignition temperature
- cutting off the air supply
- cooling the combustible material simultaneously while cutting off the air supply.
- There is a solution of sodium bicarbonate in water in the fire extinguisher and sulphuric acid in a different bottle within it.
- The sulphuric acid is combined with sodium bicarbonate solution and creates an amount of carbon dioxide gas when the fire extinguisher is operated by turning the knob on it.
- Carbon dioxide gas is not combustible, nor does it endorse combustion.
- It is heavier than air and cuts off the air’s supply of oxygen, thus extinguishing the flames.
The following reaction takes place
2NaHCO 3+H 2SO 4→Na 2SO 4+2H 2 O+2CO 2