6 Common Leakage Causes of Submersible Sewage Pumps
Submersible sewage pumps generally use mechanical seals, so the cause of leakage is mostly caused by problems with the mechanical seal. Follow the operating standards during use, check frequently during operation, and discover problems in time. It is necessary to regularly replace the wearing parts of the pump, such as bearings and mechanical seals. Only in this way can the service life of the pump be extended and the supply guarantee for normal production.
1、Leakage caused by excessive pressure
High-pressure water pumps operating under over-pressure and vacuum conditions will cause mechanical seal leakage. In the process of starting and stopping the pump, due to the blockage of the water inlet and the gas contained in the pumped fluid medium, negative pressure may appear in the seal cavity, causing dry friction on the seal end surface, causing air or water leakage in the built-in mechanical seal. The difference between vacuum seal and positive pressure seal lies in the directional difference of the sealing object, and the mechanical seal also has directional adaptability. This requires opening the valve of the relevant pipeline before starting the equipment to check the liquid level to prevent leakage caused by false-operation.
The periodic vibration of the rotor can cause periodic leakage. This is mainly due to the misalignment of the stator and the high and low end covers or the imbalance between the impeller and the main shaft. This situation will shorten the life of the seal ring. It should be inspected, repaired and adjusted in time.
3、Mechanical seal wear
This is a common cause of leakage of submersible sewage pumps. Therefore, during the normal use of the pump, the use of the pump should be checked regularly to see if there is any change. At the same time, the mechanical seal of the pump should be regularly replaced to prevent damage due to the mechanical seal. Leakage caused by damage!
4、Leakage caused by packing seal
If the pump is sealed with packing, the packing is compressed with a gland. The compression level can be adjusted by the bolt on the gland. If the pressure is too loose, the sealing effect cannot be achieved; if the pressure is too tight, the pump shaft and the packing will be mechanically worn. Large, it consumes a lot of power, and even causes the phenomenon of axle holding. Individually, the water in the water-sealed pipe may leak out in the form of drops through the gap of the filler. The pressure water in the pump casing flows into the gap between the shaft and the filler through the small holes in the water seal ring through the water seal pipe, which plays a role of cooling and smoothing.
5、Leakage of the pump leak detection ring.
On the high and low pressure bordering surface of the medium pressure pump, there is a rolling joint at the joint between the outer circle of the pump impeller and the inner wall of the pump casing, which is prone to leakage. In order to reduce the return flow of high-pressure water in the pump casing to the water inlet, two leakage reduction methods are adopted on the pump structure: (1) reduce the joint gap; (2) increase the resistance in the leakage channel.
6、leakage caused by conveying medium
If solid particles in the liquid enter the sealing end surface, it will scratch or accelerate the wear of the sealing end surface. The nominal deposition rate of scale and oil on the shaft (sleeve) exceeds the wear rate of the friction pair, so that the submersible sewage pump ring cannot compensate for the wear. The operating life of hard-to-hard friction is longer than that of hard-to-graphite friction pairs, because solid particles will be embedded in the sealing surface of the graphite sealing ring. The mechanical seal of tungsten carbide to tungsten carbide friction pair should be selected in occasions where solid particles are easy to enter.
Therefore, we must carry out investigations on time to avoid leakage caused by various reasons. Once leakage occurs, the client unit must first find out the root cause of the leakage, and replace the parts that have been damaged for a long time in time to ensure that there will be no secondary leakage.
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