In the pump device, the mechanical seal of the motorized equipment accounts for about 80%-85% of the total number of dynamic seals. In the case of pump failures, the failure of seals accounts for about half of the entire maintenance workload. It can be seen the position occupied by the seal in the maintenance of the pump. Because the medium conveyed by the machine pump varies widely and the process conditions are different, it is very important to understand these conditions for the maintenance of the machine seal.
Mechanical seals at high temperatures
To ensure that the mechanical seal works normally in a high temperature environment, the following measures can be taken.
1. Add cooling flush to mechanical seal.
2. Choose high temperature resistant materials and choose different materials according to different working temperatures. The upper temperature limit for nitrile rubber is 80°C, for silicone rubber and fluororubber 200°C, and for PTFE is 250°C. In addition, the non-metallic friction pairs in the seal are mostly made of graphite impregnated materials, so different types of impregnated graphite should be selected according to different working temperatures. Generally, the applicable temperature range of babbitt-impregnated graphite is less than 150℃, and the applicable temperature range of resin-impregnated graphite is 170~200℃. The moving ring assembly should use materials with similar expansion coefficients as much as possible to prevent the connection between the moving ring and the moving ring seat from loosening under high temperature.
3. Choose a mechanical seal with metal bellows.
For example, reduce the water content of the medium as much as possible to keep the pressure of the sealing chamber relatively stable; be equipped with a flushing cooling device as much as possible; properly preheat the sealing part before the equipment is started.
Mechanical seals at high speeds
In the case of high speed, in order to reduce the influence of centrifugal force and vibration, the rotating parts should be minimized, and the spring static structure should be adopted. It can also strengthen the cooling and lubrication of the end face of the friction pair. In addition, a friction pair material with a high [PV] value can be selected to reduce the contact width of the end face, or a controlled membrane mechanical seal can be used. In recent years, a type of seal called differential ring type has also been used in high-speed equipment. Since a differential ring is added in the middle of the original dynamic and static rings, the linear speed of the friction pair can be reduced by half, and good results have been achieved.
Mechanical seals under high pressure
To ensure the normal operation of the seal in a high-pressure environment, the high-pressure seal generally adopts a balanced structure, so that the specific pressure of the end face is in a suitable range.
Mechanical seals in corrosive environments
To ensure that the mechanical seal works normally in a corrosive environment, the seal in a corrosive environment should pay attention to the use of corrosion-resistant materials when selecting. In addition, outboard seals can be used. If the corrosiveness is very strong and easy to cause accidents, double-end seals can be used, and isolation fluid can be introduced for protection.
Seals in Particulate Media
A more effective way to do this is to add an external flushing device. Since the pressure of the flushing fluid introduced into the sealed cavity is higher than the pressure of the medium in the sealed cavity, the particulate medium can be effectively prevented from entering the sealed cavity. In addition, double-end seals can be used, and sealing liquid is added in the middle of the sealing cavity. Outer seals are also available.
The above are the maintenance methods of mechanical seals under several special working conditions. Akman Seals specializes in the production and sales of mechanical seals, and the quality of the mechanical seal materials we manufacture is guaranteed. If you are interested in mechanical seals, you can pay attention to our website.