O-rings are one of the most common seals used in machine design because they are inexpensive, easy to make, reliable and have simple mounting requirements. They have been tested to seal up to 5000 psi (35 megapascals) of pressure.
The maximum recommended pressure of an O-ring seal depends on the seal hardness and gland clearance.
The O-ring may be used in static applications or in dynamic applications where there is relative motion between the parts and the O-ring.