Main spare part of centrifugal pump
The main spare part are impeller, pump case and shaft seal device.
The impeller’s function is to transfer the mechanical energy of the prime mover directly to the liquid to increase the hydrostatic energy and kinetic energy of the liquid (mainly to increase the static pressure energy).
Impellers generally have 6 or 12 hind curved blades.
There are three types of impeller: open, semi-closed and closed.
The open impeller has no cover plate on both sides of the blade. It is simple to manufacture and easy to clean. It is suitable for conveying the material with a large amount of suspended matter. The efficiency is low and the liquid pressure is not high. The semi-closed impeller has no cover plate on one side of the suction port and a cover plate on the other side, which is suitable for conveying materials which are easy to precipitate or contain particles, and the efficiency is also relatively low. Closed impeller has front and back cover plate on both sides of blade, high efficiency, suitable for transporting clean liquid without impurity. The general centrifugal pump impeller is more such.
The impeller has two kinds of suction ways: single suction and double suction.
2, pump casing
The function is to seal the impeller in a certain space so that the impeller can inhale and press out the liquid. The pump case is made into a volute, so it is also called a volute. Due to the gradual expansion of the cross section of the passage, the velocity of the high speed liquid ejected from the impeller decreases gradually, which effectively converts part of the kinetic energy into static pressure energy. The pump housing not only collects the liquid thrown by the impeller, but also is an energy conversion device.
3,Shaft sealing device
The function is to prevent the liquid in the pump shell from leaking along the shaft or the outside air into the pump shell.
The commonly used shaft seal device has packing seal and mechanical seal two kinds.
Fillers are usually filled with soaking oil or asbestos rope coated with graphite. The mechanical seal mainly depends on the relative movement between the moving ring mounted on the shaft and the static ring fixed on the pump case to achieve the purpose of sealing.