Mechanical seal replacement and installation
The general process and method of assembling and disassembling the parts of each manufacturer is different, but the general principles of mechanical seal operation are the same. In the following, the general points that should be considered in the Mechanical seal replacement and installation are stated.
Initial shaft inspection: Make sure the shaft is clean and free of dirt, chips, and metal. Also check the area where the o-rings are located more carefully. Measure the shaft diameter to make sure it is within the tolerance allowed for the seal.
Inspect new sealing elements and parts to ensure that no damage has occurred during manufacturing or shipping. The distance between the outer diameter and the inner diameter of the plates of the connecting rings must be constant and stable. This distance may be out of the original state during the transfer. To reset, press the rings with your fingers until they return to their original position. If this issue is ignored, the amount of leakage in the sealing will be more than the permissible limit.
Adjusting the proper sealing height: To adjust this height, there are small plastic parts that must be placed on the side of the connecting rings. To install, press these parts slightly against the wall of the sealing tank. If the amount of pressure is high, the spacers will be bent and the height of the rings will be out of the proper range. After adjustment, tighten the screws and remove the spacers.
O-rings of elastometers must be installed with utmost precision and minimum pressure. Also, the amount of oil needed to install them is very small. The oil is only used to facilitate the installation of the parts and does nothing to seal the system. If too much oil is used in the mechanical seal installation, the excess oil will move to the parts where the sealing elements are in contact and have high temperature, causing burns, seal damage and leakage.
Installing the main ring: The main ring made of carbon or silicon carbide is divided into two parts, and a protective ring is used to hold these two parts. Place the main ring on the surface of the rotor and set it in the center.
One of the most important points of using and repairing a mechanical seal is the degree of tightening the seal. Due to the importance of this issue, this issue will be explained in detail below. When one of the valves in the house is leaking, tightening the valve usually fixes the problem, but if there is a large mechanical leak, over-tightening will make the problem worse. For correct adjustment, observe the following points:
Read the manufacturer’s instructions and follow them carefully
Never press the parts together. Sealing parts are easily damaged and expensive to replace.
The technician’s work space and hands must be clean. Even a small amount of contamination can damage the seal.
Do not torque the fasteners more than the required amount.
Over-tightening the gasket places unnecessary stress on the contacting surfaces. This pressure will cause the failure of the seal due to mechanical shock. Mechanical shock has reasons such as improper bearings, cavitation, high torque, unbalanced load and shaft deviation, and it is very common due to improper sealing adjustment.
Also, too much tightening will cause pressure on the springs and intensify the force between the sealing surfaces. This issue causes the sealing temperature to be higher than usual and the wear of the surfaces to occur faster. Also, one of the results of excessive tightening is the creation of distortion in the fixed elements of the mechanical seal, which causes damage to the gaskets and their deformation, which all these factors cause more leakage; So if you come across a case with a leaky mechanical seal, in most cases, loosening the seal will give better results than tightening it.