First, the buyer needs to determine the material of the O-ring.With the development of technology, more and more materials have been used in the production of O-ring, common materials are silicone rubber, epDM, nitrile rubber, hydrogenated nitrile rubber, silica gel, butyl rubber, polytetrafluoroethylene and so on.
Each of these materials has its own advantages and USES. Some are resistant to corrosion.Some high temperature resistance, some oil resistance model, some good wear resistance, and low temperature resistance, in the procurement of the need to clearly grasp the use, role, so as to be able to face a variety of O-ring materials will not be dazzled.
Secondly, it is necessary to have a clear positioning of the size and specification of O-ring. Normally, the specification of O-ring will be indicated through the outside diameter, inside diameter and line diameter. Generally, the buyer only needs to calculate the size of the inner diameter and line diameter of the O-ring to be purchased.
It is necessary to pay attention to the tolerance of O-ring specification. There are two kinds of general tolerance, one is inner diameter tolerance, the other is line diameter tolerance.The tolerance is related to the size of the product. The smaller the size, the smaller the tolerance.
Then, it is also necessary to pay attention to the compression amount of O-ring, the compression amount of O-ring is a relatively major parameter, once the wrong choice, then in the use of poor sealing, or use too tight.
How do you choose the right amount of compression?The amount of compression is closely related to the material and hardness of o-ring. For example, the hardness of O-ring is 70 degrees, so the amount of compression is 20%. Generally, the higher the hardness is, the greater the amount of compression will be.