The basic concept of head:

Head (head) - Pump the unit weight (1kg) of liquid to the work done, that unit weight of the liquid through the pump after its energy value. Marked with the letter H, used liquid column height m mark.
Other units: Pa (kPa), atm (1 atm of engineering) 1atm = 98.0665 kPa ≈ 0.1 MPa lift accounting as H = E2-E1 a high-lift pump low head use, matching motor power may exceed the rated power. Because of the characteristic curve according to the pump understood seen that when the pressure drop, the flow rate increases, the power curve is increased, and the pump power is decreased, so the pump flow and head selection is important, so that the pump to operate at its maximum power curve nearby.
Pump Hand stacker height and is used to defeat the resistance, high lift pump operation at high lift point is the description of his point of traffic flow, if the low-lift operation, the equivalent of the pump outlet resistance decreases, then the pump traffic will increase, the motor will overload, to a certain extent it will burn super motor. For example, a boiler feed pump head is 25 m, the flow of 25 m3 / h to 25 meters high when it feedwater, its flow is 25 m3 / h, when it is time to 10 meters above the water its height and resistance decreased its traffic can reach 20-50 cubic meters / hour or more, then the matching motor power will be beyond the rated power, the motor will heat or burnedThis small displacement, lifted Cheng Qian oil pump eccentric wear in severe applications geese 9-13 wells, increasing oil 6.9 tons, to the current cumulative oil 1027 tons.