1 has a good follow-up: due to the fully enclosed structure of the bellows seal itself, eliminates the necessary dynamic and static rings and the dynamic seal of the shaft sleeve (or shaft) in the ordinary spring seal, so that the elasticity of the bellows itself Fully used to form the specific pressure (but the ordinary seal due to the presence of the seal ring, in the relative displacement of the dynamic ring bushing part of the need to consume some of the balance force. The friction between the seal ring and sleeve (or shaft) to make it The size of the balance force is limited by the dimensional accuracy and heat treatment of the seal ring, showing its superior followability.In the process of use, the common mechanical seal often causes the pump body to evacuate due to fluctuations in the device or operating processes. The existence of a time-stabilizing ring seal makes it impossible to reset the end face immediately after it is opened, causing a leakage of the mechanical seal, and the sealing of the bellows machine eliminates this seal failure and is almost unaffected by the pumping of the pump body. Good compensation and performance are outstanding in pumps that are easy to evacuate, such as light hydrocarbon pumps and vacuum tower pumps. This feature is widely used in the application of bellows seals. important reason.
2 High temperature resistance Because the bellows seal eliminates the influence of the dynamic ring seal in ordinary spring seals, the applicable medium and temperature are greatly expanded. Usually, the material of the dynamic ring seal ring of ordinary mechanical seals is made of PTFE rubber, etc. Compounds, these organic compounds, in some media, react chemically with the entire body of the medium. At low temperatures and at higher temperatures, they change their physical properties and cause hardening to seal failure. Bellows seals are not limited by the above factors. Applicable to benzene, ketones, olefins, alkanes and general oils, acids, alkali salts and many other media, the temperature range can also be -250 degrees -450 degrees, of course, this also requires the strict selection of metal bellows welding and thermal repair.
3Comparison of balanced bellows seals and ordinary machine seals, no need to process the steps on the sleeve, itself can establish the balance diameter, in equilibrium (usually part of the balance) when the bellows inner and outer diameter size parameters can be Adjustment, to achieve the ideal state, the bellows machine is generally balanced in application.
4 Leakage point little moving ring and static ring sealing point are metal (non-metal) gaskets sealed and connected by bolt fastening methods, it is difficult to find the leak, in fact, the leak of the bellows machine seal is only friction seal At this point, there is no doubt that the probability is greatly reduced, and there are three major leakage channels for general mechanical seals: dynamic ring seals, static ring seals, and frictional counterfaces. In this leakage channel, seal leakage accounts for 40% of the total leakage due to failure of the dynamic and static ring auxiliary seals.
5 Shock resistance and high-speed bellows seals Axial seals are eliminated to greatly reduce the vibration of the moving ring caused by the vibration of the pump body or shaft shock caused by the transmission of the dynamic ring seal ring, so that the dynamic ring is greatly affected. It is also commonly referred to as seal floating.
When the bellows is designed as a static structure with a damping device, the damper can effectively prevent the common vibration with the shaft and the pump body generated under the condition of high line speed, so the applicable line speed is greatly improved, and its line is greatly improved. Speed up to 100M/S.
6 can reduce the spring pressure in the use of ordinary mechanical seals during the use of the spring pressure is generally designed at 0.15MPa-0.25 MPa, and the bellows seal spring pressure is generally designed between 0.05-0.15 MPa between the bellows seal for the static structure At the time, the specific pressure of the spring is significantly smaller. Therefore, the frictional heat generated by the spring pressure reduction reduces the end face temperature, thereby reducing the amount of wear on the end face during friction, ie, reducing the mechanical power consumption, improving the sealing performance and prolonging the sealing life.
7 itself can transmit torque, in the ordinary mechanical seal operation, must be additional transmission seal structure, a variety of structural forms, such as forks, pins, screws and the use of fastening to transfer torque performance, in general, without twisting Can be used normally, the structure is simplified, to avoid the failure caused by the failure of the transmission structure, improve the reliability of the seal, when the working pressure of the seal of the bellows exceeds the allowable torque, often in the structure of the structure of the fork, etc. , increase its anti-torque capacity and stability, play an auxiliary role widely used in high-pressure high-speed sealing.
8 Design a certain structure to reduce seal failure due to water scaling: In many areas, due to poor water quality, high fouling index, plus no specific demineralized water treatment device, common ring seals in the dynamic ring assist The phenomenon of seal ring failure due to water scaling has always been a chronic problem.
The design of the bellows seal into an externally cooled or static type structure can effectively prevent its fouling. If the structural design is unreasonable or improperly applied, the bellows seal is also prone to fouling, resulting in seal failure. Therefore, when bellows are recommended, Cooling water is used as the cooling water, so that the bellows sealing working environment is greatly improved and the service life is extended.
9 Remove oil seals, save costs In the general mechanical seals for pumps with high temperature and impurities, due to the limitation of the use temperature of various auxiliary seal rings and friction pair groups, the external flush oil is often injected around the friction pair (oil seal). Lubricate, reduce the temperature of the sealed chamber to create an environment suitable for the work of each component, but due to the huge waste of funds caused by oil flushing, choosing the right amount of bellows seal can save a lot of sealing funds without sealing oil.
10 The design of a certain structure can reduce the sealing failure caused by fouling of water quality: In many areas, due to poor water quality, high fouling index, plus no specific demineralized water treatment device, the dynamic ring assist in ordinary machine seals The phenomenon of seal ring failure due to water scaling has always been a chronic problem. The design of the bellows seal into an externally cooled or static structure can effectively prevent its fouling. If the structural design is unreasonable or improperly applied, the bellows seal is also prone to fouling, resulting in seal failure. Therefore, when bellows are recommended, With disposable water for cooling, it is best not to use circulating water as cooling water. The bellows sealing working environment will be greatly improved to extend the service life.
