This paper mainly describes the structure, working principle and characteristic curve of the centrifugal pump, as well as the reasonable configuration of the pump in the actual production, how to ensure the safe operation of the pump equipment in the process of using the reliability, safety and economy. Pump in tap water production line is widely used, variety specifications. Its classification methods are also different, according to their working principle can be divided into three categories: vane pumps, positive displacement pumps, other types of pumps. Most of the use in our plant is a single-stage double-suction centrifugal pump, a vane pump, the pump is due to the work of high-speed rotation of the impeller vane to spin the liquid, the liquid to obtain centrifugal force to complete the pump So the pump is called a centrifugal pump. Centrifugal pumps are used in a wide variety of applications in many sectors of the national economy. In the water supply system is almost an indispensable device, if the water pipe network as the body's vascular system, then the centrifugal pump is to send blood to the heart. As the centrifugal pump is an important equipment, and its operation to consume a lot of power! In order to rationally and economically select and use water pumps to ensure water supply to the waterworks, we must understand the working principle and basic performance of the centrifugal pumps. First, the basic structure of the centrifugal pump is composed of six parts of the basic structure of the centrifugal pump is composed of six parts are the impeller, pump body, pump shaft, bearings, seal ring, stuffing box. 1, the impeller is the core part of the centrifugal pump, its speed is high, the impeller blades play a major role in the impeller assembly before static balance experiment. The inner and outer surfaces of the impeller require smoothness to reduce the frictional loss of water flow. 2, also known as the pump casing, it is the main pump. To support the role of fixed, and with the bearing bracket to connect. 3, the role of the pump shaft is connected by a coupling and motor, the motor torque to the impeller, so it is the main component of mechanical energy transfer. 4, the bearing is set on the pump shaft supporting the pump shaft components, there are two types of rolling bearings and plain bearings. Rolling bearings using butter as a lubricant to the appropriate general size of 2/3 ~ 3/4 Too much heat, too little sound and fever! Sliding bearings are used as a transparent oil lubricant, refueling to the oil level line. Too much oil to bleed along the pump shaft and cheap, too little bearing but also overheating and burn accident! In the process of running the pump bearing temperature up to 85 degrees generally run at 60 degrees, if high, we must find out the reason (whether impurities, whether the oil is black, whether the water) and timely treatment! 5, seal ring, also known as leakage ring. The gap between the impeller inlet and the pump casing is too large, causing the water in the high-pressure area of ​​the pump to flow to the low-pressure area through this gap, affecting the output of the pump and reducing the efficiency. The gap is too small will cause the impeller and the pump shell friction wear. In order to increase the backflow resistance to reduce internal leakage, delay the service life of the impeller and the pump housing, the inner edge of the pump housing and the impeller is provided with a sealing ring at the joint of the outer support, and the sealed clearance is maintained at between 0.25 and 1.10mm. 6, stuffing box mainly by the filler, water seal ring, packing tube, packing gland, water seal tube. The purpose of the stuffing box is to close the gap between the pump housing and the pump shaft so that the water inside the pump does not flow outside and the outside air does not enter the pump. Always keep the pump vacuum! When the pump shaft friction with the filler to generate heat will depend on the water seal to live in the water seal ring so that the filler cooling! Maintain the normal operation of the pump. Therefore, during the inspection of the pump running inspection of stuffing box is a special note! Filler needs to be replaced after about 600 hours of operation. Second, the over-current centrifugal pump components Centrifugal pump over-current components are: suction chamber, impeller, pressure chamber three parts. The impeller chamber is the heart of the pump and the heart of the flow component. Pump through the impeller on the liquid work, to increase its energy. Impeller according to the direction of the liquid is divided into three categories: (1) Radial impeller (centrifugal impeller) Liquid is along the axis of the vertical direction out of the impeller. (2) Diagonal impeller (Francis impeller) The liquid flows out of the impeller in a direction inclined to the axis. (3) Axial impeller The direction of liquid flow parallel to the axis. Impeller by inhalation is divided into two categories: (1) single-suction impeller (ie impeller from the side of the inhalation of liquid). (2) double suction impeller (ie impeller suction fluid from both sides). Impeller by cover form is divided into three categories: (1) closed impeller. (2) open impeller. (3) Semi-open impeller. One closed impeller is widely used, the aforementioned single suction impeller double suction impeller belongs to this form. Third, the working principle of the centrifugal pump Centrifugal pump working principle is: centrifugal pump so water can be sent out due to the role of centrifugal force. Pump before work, the pump body and the inlet pipe must be filled with water into a vacuum state, when the impeller is rapidly rotating, the blade to promote rapid rotation of water, rotating water from the impeller in the centrifugal force of the fly, the pump After the water is thrown out, the central part of the impeller forms a vacuum area. Suwon's water pressure in the air pressure (or water pressure) under pressure through the pipe into the water pipe. This endless cycle, you can achieve continuous pumping. It is worth mentioning that: before starting the pump must be filled with water to the pump casing before starting, otherwise it will cause the pump body heat, vibration, reduce the amount of water, causing damage to the pump (referred to as "cavitation") Cause equipment accident! Many types of centrifugal pumps, classification methods are common in the following ways 1 by the impeller inhalation points: single suction centrifugal pump double suction centrifugal pump. 2 according to the number of impeller points: single-stage centrifugal pump multistage centrifugal pump. 3 according to the structure of the impeller: open impeller centrifugal pump semi-open impeller centrifugal pump closed impeller centrifugal pump. 4 according to the working pressure points: low pressure centrifugal pump medium pressure centrifugal pump high pressure centrifugal pump. 5 according to the pump shaft position points: horizontal centrifugal pump side vertical centrifugal pump. Fourth, the following centrifugal pump introduces several important performance curves. Pump performance parameters such as flow Q head H-axis power N speed η efficiency between the existence of a certain relationship. The relationship between the magnitude of their changes is represented by a curve, which is called the performance curve of the pump. Pump performance parameters between the mutual changes and mutual constraints: first of all the top speed of the pump as a prerequisite. Pump performance curve has three main curves: flow - lift curve, flow - power curve, flow - efficiency curve. A, flow - lift characteristic curve It is the basic performance of the centrifugal pump curve. Than the speed of less than 80 centrifugal pump has the characteristics of rising and falling (both in the middle convex, both sides of the bend), said the hump performance curve. Centrifugal pumps with speeds greater than 80 to 150 have flat performance curves. Centrifugal pumps with specific rotations above 150 have sharp drop performance curves. In general, when the flow is small, the lift is high, and as the flow increases, the lift gradually decreases. B, flow - power curve Shaft power is increased with the flow, when the flow Q = 0, the corresponding shaft power is not equal to zero, but a certain value (about about 60% of normal operation). This power is mainly consumed by mechanical losses. At this time the pump is full of water, if the long run, will lead to continuous temperature rise in the pump, the pump housing, bearings will be heated, may cause severe thermal deformation of the pump body, we call "stuffy head" at this time The maximum lift, when the valve is gradually opened, the flow will gradually increase, the shaft power is also slowly increasing. C, flow - efficiency curve Its curve like the shape of the hill, when the flow is zero, the efficiency is also equal to zero, with the flow rate increases, the efficiency also gradually increased, but increased to a certain value after the efficiency of decline, the efficiency of a Highest value, near the highest efficiency point, the efficiency is relatively high, this area is called the high efficiency area. V. Reasonable Allocation, Safe Operation and High-quality Water Supply After understanding the structure, working principle and characteristic curve of the centrifugal pump, how to rationally configure the power of the motor pump is the key to ensure the safe operation, high-quality water supply and reduce the production cost of the pump. , The rational allocation of pump power, pump the best work area to play a safe operation, the actual situation of our factory water supply, sufficient description of the reasonable allocation of equipment, the importance of reliability and economy. & n