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Flange/Gasket Design Considerations

FIG.4 Solid and Hollow Gaskets in Grooves

Knife Edge into Grooves with Tubular orSponge Gaskets

Large applications, such as cabinets, may use an elastomer tube orsponge with knitted mesh fitted into a groove and the mating flange known as a knife edge. The knife edge plunges into the gasket causing the seal. With tubular gaskets the knife edge collapses the gasket rather than compressing it. The knife edge should not penetrate the gasket by more than 50% of it’s diameter or there may be a danger of the gasket being unable to recover due to the excess pressure applied by the knife edge (FIG.5). This would not occur with sponge gasket types, but closure forces would be greater.

Incorrect ratio of groove andgasket result :- Gasket damageCorrect ratio:- Groove widthgreater than the gasket diameter

when the gasket is compressed by both flanges it fills theavailable space by no more than 100%, ie: the volume of the accommodating groove with both flanges touching should be equal to, but be no less than the volume of the gasket cross section.This can be calculated by dividing the height of the groovewhich, for example, would be 75% of the gasket height into the volume/area of the gasket cross section FIG 5. The same policy applies to tube or hollow gaskets, however theforces used to compress the gasket are less thus enabling fewer fixings to be used.

FIG.6 Knife Edge into Grooves with Tubular or Sponge Gaskets FIG.5 Calculating Minimum Groove Size

Gasket cross section area π
r2 Width of groove =Groove heightGasket cross section area Tubular gasket in a grooveTube collapsed by a maximum of50% of gasket height Knife edge Groove height = 75% of gasket height
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