Centrifugal pump is composed of many parts, according to the work of the work of the various parts of the state, can be roughly divided into three types: rotating parts, fixed parts and components.
1. Impeller :
Impeller is the core component of the pump, it can enable the water to get the flow of energy and produce. The impeller is composed of a blade, a cover plate and a wheel hub. When selecting the impeller material, besides considering the mechanical strength of the centrifugal force, the wear resistance and corrosion resistance of the material should be considered. At present, most of the impeller is made of cast iron, cast steel and bronze.
The impeller can be divided into single suction impeller with double suction impeller two. Single suction impeller, it is unilateral to absorb water, the front cover and the rear cover of impeller is asymmetric. Double suction impeller shown on both sides of the water, the impeller cover is symmetrical, the general flow of centrifugal pump is used for the majority of double suction impeller
Impeller according to its cover plate can be divided into three types of closed, open and semi open. Sewage pump often adopts closed impeller single channel or dual channel, to prevent blockage of the pump; it often uses a semi open and open structure, to prevent sand abrasion and blockage of the impeller.
2. Pump shaft :
Pump shaft is used to rotate the pump impeller. Commonly used materials are carbon steel and stainless steel. Pump shaft should have enough torsional strength and enough stiffness, the deflection is not more than the allowable value. Impeller and shaft with key to link. The key is to rotate between the connecting piece body, flat keys generally used in centrifugal pump, the key can only transfer torque not fixed impeller axial position, the axial position of the impeller in large and medium-sized water pump usually adopts the nut and the fastening sleeve sleeve to positioning.
3.Volute :
The water part of the water is required to have good hydraulic conditions. When the impeller works, the flow rate increases gradually along the diffuser section of the spiral case. In order to reduce the loss of hydraulic power, the flow velocity of the diffuser section of the spiral case is constant in the design of the pump. After the water is discharged from the spiral case, the pipe is pressed by a conical diffuser. The function of the conical diffuser on the spiral case is to reduce the velocity of the water flow, and to convert the part of the head of the flow velocity into the pressure head.
Material selection of the pump shell, in addition to the media to consider the flow of parts of the corrosion and wear, but also to make the shell as a pressure vessel sufficient mechanical strength.
4. Pump shell :
The pump shell is made up of a number of components, and the inner cavity of the pump is formed by the impeller working chamber, the water absorption chamber and the water pressure chamber. The shape and size of the pump shell depend on the form and size of the impeller and the shape and size of the suction chamber and the water pressure chamber determined by the hydraulic design. End cover pump shell and the impeller pump shell two main pump shell, the radial surface profile of end cap type pump shell and the pump along the axis line perpendicular to the points, the formation of the pump body and the pump cover, used for single stage pump; pump shell in open pump shell along the cutting plane through the axis of the pump the volute pump, commonly used in the double support, such as Horizontal single-stage double suction pump.
The pump body is usually made of spiral shaped. The flow velocity of the spiral case is increased continuously along the direction of the outflow, so as to reduce the energy loss due to the change of flow rate. The outlet of the water pump has a conical shaped diffusion tube, with the increase of flow section, velocity decreases, and the pressure increases, the water kinetic energy into potential energy. In the top of the pump body is provided with air or water hole, to the vacuum or irrigation water in the pump before the start.
5. Pump base:
A pump seat has a flange hole for fixing the base plate or foundation. In the pump shell bottom is provided with a drain hole, to vent water in the water pump maintenance. In addition, in the transverse groove bottom is provided with a pump discharge screw, to drain away the water leakage out of the packing box at any time.
