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Oil Seals and O Rings
An O ring is a simple form of a seal. It closes off a gap between two surfaces so that liquids or gases cannot pass through in any direction. The shape of an O ring is akin to that of a doughnut - or torus in its correct mathematical description - from which it derives its name. It is usually made from an elastomer; a viscous and elastic polymer that is a synthetic rubber or it may be formed from some other kind of thermoplastic material such as PTFE that is able to return to its original shape after being compressed.
O rings are widely used in underwater cameras to prevent water ingress and in scuba regulators to prevent the loss of air. They can also be used for light duty as drive belts. An O ring works by fitting into a pathway where gas or fluid may escape and blocking it. When pressure is applied to the system, the ring squeezes to fit into all parts of the groove. But once the pressure is taken away, the ring reverts to its original shape.
The typical O ring seal has two parts, the ring itself and a gland. The ring is the doughnut shaped moulded elastomer and the gland is a metal, or other rigid material, support inside it. This forms the seal assembly.
There is an important difference between an O ring and any other type of seal such as an oil seal. The O ring will prevent the loss of fluid or gas between two components of a system while a seal merely prevents a leakage.
Oil seals can be made from paper, real or synthetic rubber and can be found wrapped around shafts in a variety of effective ways. But in addition to sealing two surfaces, an O ring can also provide lubrication, depending on its material, such as between a piston and the piston wall.
The lifetime of an O ring or oil seal depends on its usage and the type of material from which it is made. Wear and deterioration are straightforward to identify and the seals can be replaced from the large range we supply here at Simply Bearings.