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Designing compression rate is one of the most difficult task for O-ring parameters design work and O ring is the most widely applied auxiliary seal form for mechanical seal.
Compression rate includes initial compression rate and working compression rate.
Initial compression rate mainly refers to the compression rate of O-ring seal when it is installed in the groove.This indicator mainly reflects possible installation problems caused by manufacturing tolerances of O-ring seals. Also initial compression rate changes will cause changes in working compression rate.
If initial compression rate is too large, sealing ring for the hole will be twisted in the groove. Thus，state of sealing ring will be unstable during floating process of the compensation ring, and there is a hidden danger of mechanical seal failure.
Initial compression rate will also affect performance of shaft sealing ring. If too large, shaft sealing ring will be overstretched, cross-sectional diameter of sealing ring will be reduced, working compression rate will not meet design requirements, and the mechanical seal will fail; if too small, sealing ring will fail to be loaded into the groove. Therefore, design principle of initial compression rate is: maximum value of inner diameter of the sealing ring is equal to minimum value of bottom diameter of groove on the shaft.
If working compression rate is too large,although sealing is reliable, friction and deformation will increase, and excessive wear and permanent deformation are prone to occur. Especially as auxiliary sealing element of compensation ring, O ring’s working compression rate must be suitable. If it is too large, which will cause the compensation ring to be unable to float, specific pressure of end faces of the mechanical seal will decrease, thus the mechanical seal will fail. However, if too small, the O-ring seal will be unreliable. Therefore,working compression rate is generally selected from 12% to 18%.
Compression rate includes initial compression rate and working compression rate.
Initial compression rate mainly refers to the compression rate of O-ring seal when it is installed in the groove.This indicator mainly reflects possible installation problems caused by manufacturing tolerances of O-ring seals. Also initial compression rate changes will cause changes in working compression rate.
If initial compression rate is too large, sealing ring for the hole will be twisted in the groove. Thus，state of sealing ring will be unstable during floating process of the compensation ring, and there is a hidden danger of mechanical seal failure.
Initial compression rate will also affect performance of shaft sealing ring. If too large, shaft sealing ring will be overstretched, cross-sectional diameter of sealing ring will be reduced, working compression rate will not meet design requirements, and the mechanical seal will fail; if too small, sealing ring will fail to be loaded into the groove. Therefore, design principle of initial compression rate is: maximum value of inner diameter of the sealing ring is equal to minimum value of bottom diameter of groove on the shaft.
If working compression rate is too large,although sealing is reliable, friction and deformation will increase, and excessive wear and permanent deformation are prone to occur. Especially as auxiliary sealing element of compensation ring, O ring’s working compression rate must be suitable. If it is too large, which will cause the compensation ring to be unable to float, specific pressure of end faces of the mechanical seal will decrease, thus the mechanical seal will fail. However, if too small, the O-ring seal will be unreliable. Therefore,working compression rate is generally selected from 12% to 18%.
