What is an O-Ring?
An o-ring is a donut shaped seal, generally made from an elastomer, although other materials such as plastics and metal are sometimes used.
Principals of an O-Ring
An o-ring seal closes off a passageway to prevent unwanted transfer or loss of fluids. To prevent the fluid loss or transfer the o-ring is compressed mechanically and/or under pressure against the walls of the passageway, or gland.
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Function of an O-Ring
The o-ring is contained in the gland and forced to flow into the surface imperfections, creating zero clearance and a positive block to the fluid being sealed. The pressure forces the o-ring to flow. [which is supplied by mechanical pressure, generated by gland design, material section, and by the system pressure transmitted by the fluid to the seal element.]
The o-ring seal is pressure assisted, the more pressure more effective the seal. This stands true until the physical limits of the seal are met, and the o-ring begins to extrude into the clearance gap. This scenario can be avoided with proper gland design, material selection, and the use of back-up rings.
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