First, the working principle of centrifugal pump 1 Centrifugal pump working principle Centrifugal pump working principle is that the pump is full of water, the impeller rotates to produce centrifugal force, impeller channel in the centrifugal force thrown to the periphery of the pump shell , So the impeller center pressure is reduced, the pressure is lower than the pressure in the inflow pipe, the water flows into the impeller from the sump under the pressure difference. This pump can continue to absorb water constantly supply. In addition to the role of the impeller, the role of spiral pump shell is also very important. The fluid that has gained energy from the impeller has a greater function as it flows out of the impeller. The liquid collects in the helical casing and changes the kinetic energy into pressure energy in the diffuser. Compared with other types of pumps, centrifugal pumps have the advantages of simple structure, easy to wear, smooth operation, low noise, uniform water discharge, convenient adjustment and high efficiency. Therefore, centrifugal pumps have been widely used. 2 gas binding phenomenon When there is air in the pump housing, due to the density of the air density is much smaller than the liquid generated less centrifugal force. Thus, the tank above the liquid level and the pump inlet pressure difference is not enough to liquid storage tank pressure into the pump, that is, centrifugal pump without self-suction capacity, so that the centrifugal pump can not deliver liquid, a phenomenon called "gas tied phenomenon". In order to fill the pump with liquid, a bottom valve with strainer is usually installed at the bottom of the suction pipe. The bottom valve is a check valve. The filter serves to prevent the solid matter from entering the pump and damaging the impeller or impeding the normal operation of the pump. Second, the main components of the centrifugal pump The main components are impeller, pump housing and shaft seal device. 1 Impeller The role of the impeller is the mechanical energy of the prime mover directly to the liquid to increase the hydrostatic pressure and kinetic energy (mainly to increase static pressure). Impellers generally have 6 to 12 blades after bending. Impeller has open, semi-closed and closed three. The open impeller has no cover plate on both sides of the blade, which is simple in manufacture and convenient in cleaning. It is suitable for conveying materials containing a large amount of suspended matter, which has low efficiency and low pressure of liquid to be transported. The semi-closed impeller has no cover on the suction inlet side Plate, and on the other side of the cover, suitable for conveying easily sediment or particles containing materials, the efficiency is lower; closed impeller impeller on both sides of the blade has a front and rear cover, high efficiency, suitable for the delivery of impurities Clean liquid. Most of the centrifugal pump impeller for such. Impeller has a single suction and double suction two suction method. 2 pump shell role is to seal the impeller in a certain space, so that the role of impeller suction and out of the liquid. Pump casing made of spiral shape, it is also known as the volute. Due to the gradual enlargement of the cross-sectional area of ​​the flow passage, the high-speed liquid thrown out from the impeller gradually reduces the flow velocity and effectively converts part of the kinetic energy into static pressure energy. Pump housing not only brings together the liquid thrown by the impeller, but also an energy conversion device. 3 shaft seal device is to prevent the liquid within the pump casing leakage along the shaft or outside air leakage into the pump casing. Common shaft seal packing seal and mechanical seal two. Fillers are generally impregnated with oil or asbestos rope coated with graphite. The main purpose of the mechanical seal is to achieve the purpose of sealing by the relative movement between the moving ring mounted on the shaft and the stationary ring fixed on the pump casing.
