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What are the characteristics of bellows mechanical seals?


What are the characteristics of bellows mechanical seals?
The compensation mechanism is a corrugated pipe, one of which is a sealing ring (moving ring or static ring) and the ripple control into a whole. There is no auxiliary sealing ring in the middle, so a leakage point is reduced.At the same time, the frictional resistance of the compensation mechanism is reduced, and the following is improved.For welding metal bellows seal use temperature is not restricted by auxiliary sealing ring;The sealing of the tetrafluorous bellows can be used in corrosive media.The disadvantage of bellows mechanical seal is that some corrugated pipe is less elastic and needs auxiliary spring.
There are several kinds of bellows mechanical seals.
Bellows type mechanical seal is widely used, from low temperature to high temperature, from medium to corrosive medium, from low speed to high speed, from ordinary to harsh working conditions.
All these can change the bounce rate of the bellows by changing the geometrical shape of the bellows, such as the internal and external diameter, the thickness of the wave plate and the wave number, and the elastic modulus of the material.
According to the corrosion performance of the medium, different corrugated pipe materials are selected.
For example, the neutral medium (oil and water, etc.) which are not high in working pressure and temperature, can be made of simple bellows mechanical seal made of rubber.In corrosive medium (acid or alkali etc.), it can be used for the mechanical seal of corrugated tube made of teflon.With high temperature and high speed, welding metal bellows mechanical seal can be used.
Three, metal bellows mechanical seal common failure.
1) the bellows are lost under high temperature, and the bellows burst under high pressure (such as the above hot water pump).
2. Coking and carbon deposition are easy to appear in the trough between the wave plates, causing the bellows to lose their elasticity and cannot be compensated. Therefore, they cannot be used for coking, carbon deposition and crystallization of the pump.
3) externally mounted mechanical seal, when the pressure in the sealed cavity exceeds 0.2mpa, the sealing surface can be pushed away.This is because the bellows are less elastic and cannot withstand higher medium pressure.Therefore, when the pressure is high, it is not possible to use the outer packing bellows mechanical seal.
4) due to the balance structure of the bellows mechanical seal, the effective diameter and load factor must be accounted for when using.Otherwise, in the high pressure propane and propylene pump, the work is unstable, prone to "leakage" phenomenon.

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