High Pressure O-Ring Materials:
The system operating pressure is always a consideration as it effects the choice of seal materials in several ways.
First is hardness, as may be required to resist extrusion in dynamic designs or where there is a large gap between sealed members in static applications. At very low pressures, proper sealing may be more easily obtained with lower durometer hardness (50-60 shore A). With higher pressures, the combination of pressure and material shore hardness determine the maximum clearance that may safely be tolerated.
Second is at-rest vs operating conditions and requirements for “leakless” at rest conditions which would suggest due consideration be given to the long-term compression set properties of a given material.