Main parts of centrifugal pump

1). The cap on the pump shaft through the pump, in order to prevent the high pressure water outflow and air flow through the running clearance of the pump, you must set the seal device. The seal device with filler. 

Packing box seals, packing box sealing in the centrifugal pump is widely used in the 1. Also called packing packing, are commonly used asbestos packing, asbestos graphite packing, in recent years, carbon fiber packing and PTFE packing also appeared in succession, the use effect is better than the former, but the cost is higher; the packing section for the majority of the square, it is the role of filling the gap seal, usually 4 ~ 6 ring, packing is provided with a seal ring, the outer ring is a middle concave convex ring, the seal ring alignment tube, ring provided with a plurality of small holes. When the pump is running, high-pressure water pump into the seal ring seal to infiltrate the filler through the water sealing pipe, but also has the effect of cooling and lubricating pump shaft. The packing of the gland to adjust screw. If the pressure is too tight, although can reduce leakage, but the packing and shaft friction loss increased, the power consumption is large, or even axle phenomenon, the shaft excessive wear; pressure too loose, is not up to the sealing effect. Therefore, the sealing parts should be kept 25 to 150 drops per minute is appropriate, but the specific pump should be based on the requirements of the specification to control the frequency of dripping water. 

2).  Mechanical seal, also known as end face seal. The mechanical seal is mainly depend on the pressure of the liquid pressure and the pressing element, make the appropriate pressure seal and maintain a very thin liquid film and achieve the purpose of sealing. 

 Mechanical seal is not balanced, balanced and other types of. The pressure on the seal face of the non balanced mechanical seal is determined by the pressure of the sealing medium, the medium pressure is increased, and the ratio of the end face is increased in proportion to the pressure. If the face of the pressure is too large, it may cause serious leakage, life expectancy, and therefore non - balanced mechanical seals should not be used under high pressure. The specific pressure on the sealing end face of the balanced mechanical seal is increased slowly, that is, the pressure of the medium is less than the pressure of the end face, so the balance type can be used for the mechanical seal under high pressure. 

The outer circle of the impeller suction population and the inner wall of the pump casing have a rotary joint, which is a high and low pressure interface, and has the relative movement of the parts. If the gap is too large, then the high pressure water pump body will be through the gap to leak back into the suction side of the impeller, thereby reducing the efficiency of the pump; if the gap is too small, the rotation of the impeller and the pump body will be friction, especially when the water containing sand will aggravate the friction. In order to protect the impeller and the pump body, in order to reduce the leakage loss, the impeller is installed on the suction port or shell of the missing ring. The missing ring has a single ring, double ring and double ring labyrinth. 

The bearing is used to support the weight of the rotating part and the axial force and radial force of the bearing. Generally speaking, the horizontal pump with radial force, vertical pump with axial force. Some large pump in order to reduce the temperature of the bearing and the bearing cooling water jacket is arranged on the bearing, the bearing cooling cycle with clean water. 

Large and medium-sized water pump (general pump shaft diameter greater than 75ram) often used bronze or iron (Babbitt lining) metal sliding bearing manufacturing, oil lubrication. Also has the use of rubber, synthetic resin, graphite and other non - metal materials made of plain bearings, can be used for water lubrication and cooling.. 

The output of the motor is transmitted through the coupling to the feed pump. Coupling also known as the "back" wheel, there are two kinds of rigid and flexible. Rigid coupling is in fact the two round flange connection, no adjustment in the connection, therefore, the requirements of high precision, commonly used in small pump units and vertical pump unit connection. Flexible coupling is generally used in the installation of large and medium sized horizontal pump units. Commonly used disk flexible coupling. It is actually a steel pin coupling with elastic rubber ring, including two discs, with the flat keys respectively pump shaft and the motor shaft are connected in the pump unit operation, should regularly check the rubber ring intact, so as not to occur due to change of elastic rubber ring "and failed to wear, resulting in steel the pivot and disc hole direct friction, causing Kong Mocheng to lose round ellipse or phenomenon. Magnetic pump in addition to including coupling, also need to include magnetic drive device.