Fire pumps for fire-fighting water infrastructure

1) Working principle. The main type of fire pump used in the fire water supply system is centrifugal pump. The work of this pump is carried out by centrifugal force, see Figure 4-4. Before the pump starts, the pump casing needs to be filled with water. When starting, the drive through the pump shaft to drive the impeller rotation, the impeller on the raised blades will make the water along with the rotation. The water is thrown into the outlet pipe under the action of centrifugal force and, at the same time, a vacuum is formed in the suction pipe. The external water will enter the pump through the suction pipe under the action of atmospheric pressure. In this way, the water will be continuously pressurised by the pump and delivered out.

Fire pump selection

(1) The performance of the fire pump should meet the requirements of the fire water supply system required flow and pressure.

(2) fire pump with the drive power should meet the selected pump flow head performance curve at any point in the operation of the power requirements. (3) When the use of motor-driven fire pumps, the motor should be selected dry installation of fire pumps

(4) Flow head performance curve should be no hump, no inflection point of the smooth curve, zero flow pressure should not be greater than 140% of the design working pressure, and should be greater than 120% of the design working pressure.

(5) When the output flow rate is 150% of the design flow rate, the outlet pressure should not be less than 65% of the design working pressure.

(6) The sealing method and material of the pump shaft shall meet the requirements of the fire pump operating at low flow rate.

(7) fire water supply to the same pump group of fire pumps should be the same model, and the work of the pump should not be more than 3 units.