WHAT DO YOU KNOW ABOUT MECHANICAL SEAL AND CONTROL OF CENTRIFUGAL PUMP?

For many reasons, the dynamic seal seat of the mechanical seal cannot be effectively compensated. The sealing surface of the mechanical seal is frequently opened, and the medium flows through the sealing surface to erode the sealing element, impurities enter the sealing surface, and the sealing element is worn. These conditions will cause seal failure.

ANALYSIS OF THE CAUSE OF MECHANICAL SEAL FAILURE OF CENTRIFUGAL PUMP

1. The Sealing Surface Is Opened

1) The sealing surface is opened due to excessive vibration caused by insufficient tightening of the equipment, inadequate leveling and alignment, equipment cavitation, bearing damage, and poor foundation rigidity.

2) The thrust surface is worn, the thrust bearing is damaged, and the compensation mechanism causes insufficient compensation force, which causes the sealing surface to open.

2. Reduced Sealing of Auxiliary Parts

1) Due to inadequate cleaning during installation, a gap is formed between the impurities and the adjacent parts of the auxiliary seal, which reduces the sealing performance and even damages the auxiliary seal.

2) When installing the auxiliary seal, the selected auxiliary seal diameter or circumference is too small, the seal elasticity is too small and high temperature resistance lead to insufficient compensation. Or the selected auxiliary seal material is not resistant to corrosion and hardening and loses its ability to compensate.

3. Influence of Medium

Since the physical and chemical properties of the transported medium will affect the physical and chemical properties of the mechanical sealing element, the sealing performance will be reduced. Mechanical impurities cause wear on the sealing surface and reduce the sealing performance.

INSTALLATION OF MECHANICAL SEALS FOR CENTRIFUGAL PUMPS

1. Principles of Centrifugal Pump Installation

First of all, you should be familiar with the use status and environment of the centrifugal pump, understand the operating speed and shaft diameter, before installation, consider the mechanical seal production process and related parameters of the seal cavity, equipment service conditions and management technology level.

2. Installation of Mechanical Seal

1) Preparation

The model and specifications of the mechanical seal should be verified before installation. Check the overall condition of the mechanical seal, keep it intact and tidy, and check the integrity of the moving ring and static ring without damage. Check the parts prone to problems to ensure that there are no burrs and grooves. In order to facilitate the installation, the machine oil should be applied to the shaft and sleeve, gland and sealing ring.

2) Installation Sequence

First, install the static part of the mechanical seal, and install the anti-rotation pin into the hole of the seal end cap. Then install the static ring and the seal ring according to the order, and then install the static ring into the sealed end cap. After installing the static part, install the moving part of the mechanical seal device, install the moving parts of the mechanical seal device in order on the shaft, and install them one by one to avoid misalignment.

MAINTENANCE OF MECHANICAL SEAL MECHANISM OF CENTRIFUGAL PUMP

1. Maintenance before Startup

Before starting to install the centrifugal pump, a comprehensive inspection of the system should be carried out, including inspection of various accessories and the main body of the mechanical seal mechanism. Determine the mechanical seal mechanism by static pressure test and check whether there is a leak in the entire mechanism. Before starting, ensure that the liquid in the sealed cavity is full and the air is emptied.

2. Maintenance during Operation

If a small amount of leakage occurs during operation of the centrifugal pump, the leakage should be evaluated. Carry out regular inspections on the tightness of the machine. The sealing surfaces of the moving ring and static ring should be checked during the maintenance of the sealing mechanism, and they should be replaced and repaired in time.

3. Daily Maintenance

In the routine inspection and maintenance process, everyone often has some misunderstandings. In fact, the compression of the spring during installation is not as large as possible, the dynamic ring seal is not as tight as possible, and the static ring seal is not as tight as possible.

The centrifugal pump will cause its leakage due to various factors during actual installation and use. Summarizing the above analysis, it can be explained that the installation and maintenance of mechanical seals should be carried out according to standard procedures, and the causes of various leakage problems should be clarified, so as to make targeted treatments, so as to ensure the sealing effect from installation to maintenance.