Understand fire pump flow head performance curve is the key to the selection

fully understand the performance of fire pump, familiar with the characteristics of the lift fire pump performance curve, grasp its change law of form a complete set of rational selection of fire pump, the right to determine the fire pump installation height of pump, fire pump pump operation condition adjustment and strengthening the pumping stations scientific management is very important, is also a key elements of the fire pump selection!

a, the selection and application of fire pump shall meet the following requirements:

the selection of fire pump should meet the demand of fire water system of flow and pressure, is the most basic technical regulations of fire water pump selection;

2 fire pump shall meet the selected the power of the drive for the pump flow head any running the required power demand on the performance curve;

3 motor wet when installation and maintenance difficulties, sometimes will empty fire pool to maintenance, which reduces the reliability of fire water. The motor in the water, cable leakage can bring dangers to operators and system, therefore from the safety and reliability and maintainability, the provisions of this specification by dry motor installation;

4 the operation of the fire pump may be in any one of the water pump performance curve, therefore to lift its flow performance curve should be smooth without hump, this can avoid the surge of pump operation. Fire water pump when zero flow pressure should not exceed 140% of the rated design pressure is to prevent the system in the small flow run time pressure is too high, cause system pipe network investment is too large, or excessive overpressure systems. When zero flow, the pressure should not be less than 120% of the rated pressure because of the fire water system control and prevent overpressure is accomplished by pressure, if the fire pump performance curve is not a certain slope, and hydraulic pressure control has the certain difficulty, thus provides the fire pump zero flow when the pressure of upper and lower limits.

5 when the flow as the design flow of 150%, the outlet pressure should not be less than 65% of the design work pressure;

with the drive by fire pump power should satisfy the selected pump flow running on any lift performance curve including design flow 150% flow when the power requirements.

       Q— — Fire protection design flow.

       H— — When designing fire flow pump head.

       H0— — Zero flow when the pump head.

       N— — Power.

2, fire pump performance curve

1, fire pump performance curve of pump is under a certain speed, flow as basic variables, other parameters change with flow and the curve changes, mainly includes:

1) And flow rate Q - Lift H curve ( Q - H) : it means the flow and the relationship between the pump head.

       2） And flow rate Q - N power curve ( Q - N) : it means the flow and pump power relationship.

       3） And flow rate Q - Eta efficiency curve ( Q - η) : it means the flow and pump efficiency relations.

2, for the arbitrary traffic point of fire pump, all can through characteristic curve, the curve to find out its relative lift, power and efficiency.

3, under normal circumstances, the rated flow and head of the fire water pump parameters (such as The design flow and design pressure) , the best efficiency point and collocated or close.

three head, fire pump performance curve

the performance of the fire pump should meet the requirements of fire water system required flow rate and pressure, the flow of the pump head performance curve, is the key elements of the model selection of the pump.

1, the flow of the pump head performance curve should be smooth curve of hump, inflection point, and need a certain slope, in order to realize the pressure and the hydraulic control.

2 zero flow, water pump in the pressure should not be greater than 140% of the design work pressure, and should be greater than 120% of the design work pressure;

       1） , fire pump zero flow when the pressure should not exceed 140% of the rated design pressure is to prevent the system in the small flow run time pressure is too high, cause system pipe network investment is too large, or excessive overpressure systems.

       2） When, zero flow, the pressure should not be less than 120% of the rated pressure, because of the fire water system control and prevent overpressure is accomplished by pressure, if the fire pump performance curve without a certain slope, and hydraulic pressure control has the certain difficulty, thus provides the fire pump zero flow when the pressure of upper and lower limits.

3, when 150% of the water pump outlet flow as the design flow, the outlet pressure should not be less than 65% of the design work pressure;

in the process of fire fighting and rescue work, super traffic is inevitable, shall ensure that the work of the super flow when a certain pressure.

4, in the application in the selection of fire pump, not monotonous falling water pump performance curve is used, cannot use the performance curve hump-like shape of water pump, water pump performance curve is a turning point will not be used.

5, many sets of fire pump in parallel, the superposition of traffic head performance curve will have change, should check the flow superposition effect on the fire pump outlet pressure.

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