Working principle of centrifugal pump
The impeller is installed in the pump housing 2, and is fastened to the pump shaft 3, the pump shaft is directly driven by the motor. The central pump housing has a liquid suction 5 and the suction pipe 4 connected. The liquid through the bottom valve 6 and the suction tube into the pump. Liquid discharge port 8 on the pump casing and the discharge pipe 9.
Before the start of the pump, the pump casing is filled with the liquid; the impeller is driven by high speed rotation, and the liquid between the blades must rotate along with the rotation. Under the action of centrifugal force, liquid from the impeller center thrown toward the outer edge and get the energy, to speed away from the outer edge of the impeller in the pump shell shaped cochlea. In the case of the spiral case, the liquid is slowed down by the gradual expansion of the flow channel, and the part of the kinetic energy is changed into static pressure energy, and finally, with the higher pressure, the liquid is discharged into the pipe and sent to the need. Liquid from the outer edge of the impeller center flows, in the center of the impeller formed vacuum, due to the pressure on the top of the tank liquid level is greater than the pressure pump at the entrance, the liquid will be continuous pressure into the impeller. Can be seen, as long as the impeller continues to rotate, the liquid will continue to be inhaled and discharged.
Gas binding phenomenon
When the pump casing has the air, the density of the air is much smaller than that of the liquid. Thus, the tank above the liquid surface and pump suction pressure at the mouth of the poor to presses the liquid in the storage tank into the pump, centrifugal pump without self absorption capacity, the centrifugal pump can transport the liquid. This phenomenon called "gas tie situation".
In order to make the pump full of liquid, usually in suction pipe is arranged on the bottom of the bottom area of the screen, the valve until the end non-return valve, the function of filter is prevent solids into the pump impeller damage or interfere with pump normal operation.
Two, the main parts of the centrifugal pump
The main components have impeller, pump shell and the seal device.
1, impeller
The role of the impeller is the original motivation of the machine can be directly passed to the liquid to increase the static pressure energy and kinetic energy (mainly increase the static pressure).
The impeller generally has a 6~12 blade and a curved blade.
Impeller has three kinds of open, semi closed and closed, as shown in Figure 2 - 2.
Open impeller blades at both sides no cover, simple manufacturing, convenient cleaning, suitable for contained in the transmission of a large number of suspended solids material, low efficiency, transmission of liquid pressure is not high; semi closed impeller in the intake side of no cover, and on the other side of the cover, suitable for conveying easy or precipitation particles containing material, the efficiency is low; closed impeller at the impeller blades at both sides have front and back cover, high efficiency is to transport does not contain impurities in the cleaning liquid. General centrifugal pump impeller for this type.