O-Ring seal is a common seal .
It is for use in machine design.
O-ring seal can be use in static application such as cover or pin. If the machine parts being seal move relative to one another, the o-ring acts like a dynamic seal.
Easy to craft , reliable , inexpensive.
A packing device .
Commonly moulded in one piece from elastometric material.
Also use to offer structural support ,absorb energy, transmit energy, transmit fluid and seal fluid.
O-ring acts like a seal just by blocking any leaking of gas or liquid between two close mating surface.
O-ring are utilize to keep the air or fluid in/out of distinct space.
It is use in under water camera in order to keep the water out.
SCUBA regulator use O-rings to avoid air from moving out.
Also,use in automobile parts ,cups , drive , belts,body jewellery.
O-RINGS are made from rubbers, metals and plastics.
STATICS v/s DYNAMICS SEALING
O-ring also called Toric joint
If the pressure of fluid contain is not greater than the mating stress of o-ring ,then sealing is completed.
To meet the explicit performance requirement of special seals like”ENERGIZED HYDRULIC SEALS” and ”OIL SEEDS” are available.
In vaccum system that must be immerse in liquid nitrogen utilise indium o-ring.
Rubber become brittle and hard at lower temperature.
High vaccum system make use of nickle or copper o-ring.
O-rings come in a variety of sizes. Society of Automotive Engineers (SAE) Aerospace Standard 568 (AS568) specifies the inside diameters, cross-sections, tolerances, and size identification codes (dash numbers) for O-rings used in sealing applications and for straight thread tube fitting boss gaskets. British Standard (BS) which are imperial sizes or metric sizes. Typical dimensions of an O-ring are internal dimension (id), outer dimension (od) and thickness / cross section (cs)
Metric O-rings are usually define by the internal dimension x the cross section. Typical part number for a metric O-ring – ID x CS [material & shore hardness] 2x1N70 = defines this O-ring as 2mm id with 1mm cross section made from Nitrile rubber which is 70Sh. BS O-rings are define by a standard reference.