O-Ring Sizes Catalogue

O-Ring Sizes and Material Selection

Download Metric O-Ring Sizes and Standard Sizes Chart (PDF)

O-Ring Standard Size AS 568A, BS 4518, GB/T 3452.1, JIS B 2401, Metric, Swedish SMS 1586

Of the many kinds of sealing technology available in products manufacturing and machine design, the use of the o-ring is perhaps the most common and extensive. O-rings are used in appliances found in our homes as well as in heavy industrial machines like hydraulic cylinders and jacks. They are also typically found in many types of hand tools like pneumatic hammers, drills and air tools.

The selection of the right o-ring sizes is of critical importance and the sizes of o-rings are determined by its internal diameter as well as the diameter of its cross section area. The o-ring, when installed into the mount, should seat nicely and with strict tolerance within the recess of the mounting. The surface of the mounting that comes into direct contact with the o-ring should be even so that pressure on the o-ring is distributed evenly throughout. The o-ring, when compressed, should exert a pressure against the contact surface of the mounting of a value that is greater than the pressure of the fluid to be contained. This is essential for the proper sealing of the fluid and ensures that no leakage will occur. The selection of the o-ring should therefore be made with the design and shape or size of the mounting contact surface into consideration. The wrong size o-ring will result in sealing failure.

Environments where sealing components are subject to abuse include that of extreme temperatures conditions as well as exposure to corrosive chemical media. Elastomeric seals have to perform under the most demanding conditions, and failure would have implications in terms of equipment downtime, environmental consequences and safety of operation.