Causes and treatment methods of damage to the mechanical seal of centrifugal pumps
There are six reasons why the centrifugal pump seal is damaged. The specific content and treatment methods of each item are as follows:
1. The water used by the centrifugal pump is of poor quality and contains particles. Due to poor water quality, small particles and high hydrochloride content in the medium, abrasive wear occurs on the plane of the centrifugal pump seal or the surface is strained to produce grooves and rings. Solution: Improve the water pressure or medium, and replace the mechanical seal.
2. Cavitation. Cavitation (mainly caused by hot centrifugal pumps). Since the medium is hot water, the water temperature is too high to generate steam, and the gas in the pipe enters the high part of the pump chamber. This part of the gas cannot be discharged, resulting in water shortage operation, dry grinding failure of the mechanical seal, and cavitation of the device. Solution: Replace the machine seal.
3. Lack of water causes dry grinding damage during operation. This phenomenon is often seen in the negative pressure at the inlet of the type installation. There is air in the water inlet pipe and air in the pump cavity. After the pump is started, the friction of the mechanical seal generates high temperature when running at high speed and cannot be cooled. Check the mechanical seal. The spring tension is normal and the friction The surface is burnt and black, and the rubber becomes hard and cracked. Solution: Exhaust the air in the pipeline and pump chamber, and replace the mechanical seal.
4. If the installation is too tight, observe the dynamic and static ring planes of the mechanical seal. If there is severe scorching, the plane will turn black and have deep marks, the sealing rubber will become hard and lose its elasticity. This phenomenon is caused by installation that is too tight. Solution: Adjust the installation height. After the impeller is installed, use a screwdriver to move the spring. The spring has strong tension and will reset after loosening. A moving distance of 2-4mm is sufficient.
5. Water leaks from the mechanical seal. Treatment method: Fill the leaking gap with high-density material, or replace the mechanical seal.
6. The installation is too loose. Observe the plane of the dynamic and static ring of the machine seal. There is a very thin layer of scale on the surface, which can be wiped off. There is basically no wear on the surface. This is caused by the loss of spring elasticity and poor assembly, or caused by the axial movement of the motor. Treatment method: Replace the spring, motor shaft, and reassemble.
