O-rings are the most widely used seals in hydraulic and pneumatic systems, but improper selection, groove design, machining, and assembly often lead to oil leakage. Before selecting a seal, it is essential to understand the application scenario: is it a dynamic or static pressure seal, and is it internal or external pressure? Only by clarifying the application scenario can the correct seal be selected.
The main considerations for external pressure include:
Support and constraint: External pressure provides support and constraint for the O-ring, helping it maintain its shape and position within the gland. This support prevents the O-ring from shifting or being squeezed into the gap, thus ensuring a consistent and effective seal.
Balancing internal pressure: External pressure helps balance the internal pressure acting on the O-ring. By applying pressure to the outer diameter, external pressure helps resist the squeezing effect caused by internal pressure, thereby improving overall sealing performance.
Under internal pressure: The outer diameter of the O-ring is the same as the outer diameter of the groove; under external pressure: The inner diameter of the O-ring is the same as the inner diameter of the groove. It is important to prevent the O-ring diameter from shrinking under operating pressure.
