Selection Of Propane O-rings And Matters Needing Attention

Propane o-rings is one of the most commonly used seals. But because of the improper selection, groove design, processing and assembly, often resulting in oil leakage failure, can be described as a small bad event.

The national standards for the size of propane o-rings in China include GB1235-76, GB3452.1-88 and GB3452.1-92. The section diameters of propane o-ringss specified in GB1235-76 are 1.9,2.4,3.1,3.5,5.7, etc. , the propane o-rings adopts the marking method of "outer diameter line diameter", which is generally called the old national standard; GB3452.1-82 is basically the same as GB3452.1-92 and is generally called the new national standard. The section diameters of propane o-rings are 1.8,2.65,3.55,5.3, etc. , the new National Standard uses the International Convention, the propane o-rings uses "the inside diameter line diameter" the marking method.

When selecting the propane o-rings, the new national standard should be selected as far as possible at first. The diameter of 2.65 and 3.55 are the most commonly used, and the propane o-rings of 3.55 should be selected as far as possible when the outer diameter is larger than 30 or so and the structure size is allowed, to achieve greater compression and contact area.

The material of propane o-rings mainly includes Butadiene cyanogen rubber NBR and fluorine rubber FKM, fluorine rubber is more suitable for high temperature working condition.

In addition to the material, propane o-rings is a very important indicator of its hardness, generally using shore hardness to express, from about 60 to 90, the greater the number of hardness is higher. Under the same pressure, the higher the hardness, anti-extrusion (deformation and even tear) the ability of the stronger. Therefore, should choose a higher hardness of the propane o-rings.

However, the commonly used propane o-rings in the market are made of butadiene-cyanogen rubber, shore hardness is generally about 70, it is difficult to meet the requirements of a considerable part of the operating conditions.

propane o-rings groove design has relevant national standards, the main dynamic seal, axial static seal and radial static seal three kinds. The propane o-rings of Flange and cover is compressed axially to ensure the sealing performance. In addition, the standard of groove size in our national standard has fallen behind. For example, the outer diameter of propane o-rings groove under internal pressure is equal to the outer diameter of propane o-rings, while the outer diameter of propane o-rings groove of Parker flange joint is less than the outer diameter of propane o-rings. Foreign Standards Shall Be Duly referred to in the design.

The sealing surface with propane o-rings shall not use flat sealant, propane o-rings can be coated with a small amount of butter so that it does not fall off. In maintenance, should be based on the groove size to determine the propane o-rings specifications, is not the diameter of the rougher the better.