Basic parameters of pump
The basic parameters characterizing the main performance of the pump are the following:
1. The flow Q
Flow rate is the amount of liquid (volume or mass) that the pump has delivered per unit of time.
Volume flow with Q, said the unit is: m3/s, m³/h, l/s, etc..
Mass flow with Qm, the unit is: kg/s, t/h, etc..
The relationship between mass flow and volume flow is:
Qm= P Q
P - liquid density (kg/m3, t/m3), room temperature water P =1000kg/m3.
2. Head H
Head is the pump pumping unit weight of the liquid from the inlet of the pump (pump inlet flange) to the outlet of the pump (pump outlet flange) energy value. Is a Newtonian fluid obtained through the effective energy of the pump. The unit is N, m/N=m, the height of liquid column pumping liquid, used for short meters.
3. Speed n
Speed is the pump shaft revolutions per unit time, represented by the symbol n, the unit is r/min.
4. The cavitation margin NPSH
The suction head is also called the net positive suction head, which is the main parameter that indicates the cavitation performance. Cavitation has been used h said.
5. Power and efficiency
Pump power is usually refers to the input power, that is, the original motive power transmitted to the pump shaft, it is also known as the axis power, with P said;
The effective power of the pump is also called the output power, which is expressed by Pe. It is a unit of time from the pump to pump the liquid in the pump to get the effective energy.
Because the lift is refers to the output of the pump unit weight of the liquid from the pump energy efficient, so the product of the head and the mass flow rate and the acceleration of gravity is in unit time from the pump output liquid obtained by effective energy - that is, the effective capacity of the pump:
Pe= P gQH (W) = QH (W)
P: the density of liquid pumping (kg/m3);
Gamma - pump delivery fluid of severe (N/m3);
Q - pump flow (m3/s);
H - pump head (m);
G - gravity acceleration (m/s2).
The difference between the shaft power P and the effective power Pe is the pump power, and the size of the pump is measured by the efficiency of the pump. The efficiency of the pump as the effective power and shaft power ratio, with ETA said.
