How to tell the quality of the seal

O-rings are mainly used for static sealing and reciprocating sealing to prevent leakage of media such as liquids and gases.
What are the conditions for a qualified seal:
1. Be flexible and resilient.
2, to have appropriate mechanical strength, including tensile strength, elongation and tear strength.
3. It has stable chemical properties, is not easy to swell in the medium, has small heat shrinkage rate, does not decompose at high temperature, does not soften, does not harden at low temperature, and does not affect the use.
4, good resistance to oxygen and aging, durable.
5, does not corrode the contact surface, does not pollute the medium.