(1) Working principle
1) The working principle can be divided into blade type, volume type and other forms.
Vane pumps, relying on the dynamic action of the rotating impeller on the liquid, continuously transfer energy to the liquid, so that the kinetic energy (mainly) and pressure energy of the liquid are increased, and then the kinetic energy is converted into pressure energy through the press-out chamber. Divided into centrifugal pump, axial flow pump, partial flow pump and vortex pump.
Positive displacement pumps, relying on the periodic change of the volume of the sealed working space containing the liquid, transfer energy to the liquid periodically, so that the pressure of the liquid is increased to force the liquid to be discharged, and can be divided into reciprocating pumps according to the movement form of the working element And rotary pump.
Other types of pumps transfer energy in other forms. For example, the jet pump relies on the high-speed injection of working fluid to suck the fluid to be transported into the pump and mix it to exchange momentum to transfer energy; the water hammer pump uses part of the water flowing during braking to be raised to a certain height to transfer energy; the electromagnetic pump makes The energized liquid metal flows under the action of electromagnetic force to realize transportation. In addition, pumps can also be classified according to the nature, driving method, structure, and use of the conveyed liquid.
2) Classified by the number of working impellers
Single-stage pump: that is, there is only one impeller on the pump shaft. Multi-stage pump: that is, there are two or more impellers on the pump shaft. At this time, the total head of the pump is the sum of the heads produced by n impellers.
3) Classified by work pressure
Low pressure pump: the pressure is lower than 100 meters water column; Medium pressure pump: the pressure is between 100 and 650 meters water column; High pressure pump: the pressure is higher than 650 meters water column. (Multistage centrifugal pump can reach 2800m)
4) Classified according to the way of impeller water inlet
Single-side inlet pump: also called single-suction pump, that is, there is only one water inlet on the impeller; Double-side inlet pump: also called double-suction pump, that is, there is an inlet on both sides of the impeller. Its flow rate is twice that of a single-suction pump, which can be roughly regarded as two single-suction pump impellers put together back to back.
5) Classified according to the joint seam of the pump casing Horizontally split pump: There is a joint seam on the horizontal plane passing through the axis line. (The most common horizontal split pump is a double-suction pump) Vertical joint surface pump: the joint surface is perpendicular to the axis line. 6) Classified by pump shaft position Horizontal pump: The pump shaft is in a horizontal position. Vertical pump: The pump shaft is in a vertical position.
7) Classified according to the way that the water from the impeller is led to the extrusion chamber
Volute pump: After the water comes out of the impeller, it directly enters the pump casing with a spiral shape. Guide vane pump: After the water comes out of the impeller, it enters the guide vane set outside it, and then enters the next stage or flows into the outlet pipe. (Commonly used in multi-stage pumps and axial flow pumps)
(2) Principle of operation
An impeller composed of several curved blades is placed in a pump casing with a volute passage. The impeller is fastened to the pump shaft, and the pump shaft is connected with the motor, which can be driven to rotate by the motor. The suction port is located in the center of the pump casing and is connected to the suction pipe, and a check valve is installed at the bottom of the suction pipe. The side of the pump casing is the discharge port, which is connected with the discharge pipeline and is equipped with a regulating valve.
The reason why centrifugal pumps can transport liquids mainly depends on the centrifugal force generated by high-speed rotating impellers, so they are called centrifugal pumps.