Centrifugal water pump

Centrifugal force is actually a manifestation of the inertia of an object. For example, when the umbrella rotates slowly, the water droplets on the umbrella will rotate with the umbrella. This is because the friction between the umbrella and the water droplets acts as the centripetal force for the water droplets. However, if the umbrella rotates faster, the friction is not enough to make the water droplets move in a circular motion. Then the water droplets will break away from the umbrella and move to the outer edge, just like using a rope to pull a stone to do a circular motion. If the speed is too fast, the rope will break and the stone will fly out. This is the so-called centrifugal force.

The centrifugal pump is designed based on this principle. The high-speed rotating impeller blades drive the water to rotate and throw the water out, thereby achieving the purpose of transportation.

There are many types of centrifugal pumps. From the perspective of use, they can be divided into civil and industrial pumps; from the perspective of the conveying medium, they can be divided into clean water pumps, impurity pumps, corrosion-resistant pumps, etc.

Working principle of centrifugal pumps

The centrifugal pump is composed of six parts, namely: impeller, pump body, pump shaft, bearing, sealing ring, stuffing box.

1. The impeller is the core part of the centrifugal pump. It has high speed and high output force. The blades on the impeller play a major role. The impeller must pass the static balance test before assembly. The inner and outer surfaces of the impeller are required to be smooth to reduce the friction loss of the water flow.

2. The pump body is also called the pump shell, which is the main body of the water pump. It plays a supporting and fixing role and is connected to the bracket for installing the bearing.

3. The function of the pump shaft is to connect with the motor through the coupling and transmit the torque of the motor to the impeller, so it is the main component for transmitting mechanical energy.

4. The bearing is a component that supports the pump shaft and is sleeved on the pump shaft. There are two types: rolling bearings and sliding bearings. Rolling bearings use butter as a lubricant. The oil should be appropriate, generally 2/3 to 3/4 of the volume. Too much oil will heat up, too little will make noise and heat up! The sliding bearing centrifugal pump structure uses transparent oil as a lubricant, and the oil is added to the oil level line. Too much oil will seep out along the pump shaft and float, too little bearing will overheat and burn out, causing accidents! During the operation of the water pump, the temperature of the bearing is as high as 85℃ and generally runs at around 60 degrees. If it is high, find the cause (whether there are impurities, whether the oil is black, whether water has entered) and deal with it in time!

5. The sealing ring is also called the leakage reduction ring. If the gap between the impeller inlet and the pump casing is too large, the water in the high-pressure area of the pump will flow to the low-pressure area through this gap, affecting the water output of the pump and reducing the efficiency! If the gap is too small, the impeller and the pump casing will cause friction and wear. In order to increase the reflux resistance and reduce internal leakage, and delay the service life of the impeller and the pump casing, a sealing ring is installed at the junction of the inner edge of the pump casing and the outer aid of the impeller, and the sealing gap is preferably kept between 0.25 and 1.10mm.

6. The stuffing box is mainly composed of packing, water seal ring, packing cylinder, packing gland, and water seal pipe. The main function of the stuffing box is to close the gap between the pump casing and the pump shaft, so that the water in the pump does not flow to the outside and the outside air does not enter the pump. Always keep the vacuum in the water pump! When the pump shaft and the packing generate heat through friction, the water seal pipe will be used to keep the water in the water seal ring to cool the packing and maintain the normal operation of the water pump. Therefore, special attention should be paid to the inspection of the packing box during the inspection of the water pump operation. The packing should be replaced after about 600 hours of operation.