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Squeeze
Initial design squeeze or compression provides for low pressure sealing. Depending on the cross section (CS), a
squeeze from 10% to 35% is recommended. Higher percentage squeeze may be tolerated in static seals where friction
and wear are not considerations. In dynamic service, it is often desirable to reduce O-Ring compression to a minimum.
As a rule, design squeeze should not fall below 0.010 inch.
Pressure
Up to a certain point, sealing is enhanced by pressure. However, pressure may cause an increase in friction and
wear. Above 1500 psi, pressure may cause extrusion and seal failure in a standard gland configuration. An anti-
extrusion back-up ring, made of a tough, cut-resistant material such as leather, PTFE, or hard rubber, is suggested.
In static applications, it may be possible to modify the gland design to withstand the higher pressures without the
addition of a back-up ring.