Selection Of Propane O-rings And Matters Needing Attention

Propane o-rings is the most commonly used seal in sealing. However, due to improper selection, groove design, processing and assembly, oil leakage failures are often caused, which can be described as a small and bad thing.

When selecting propane o-rings, the new national standard should be selected first. The wire diameters of 2.65 and 3.55 are most commonly used. When the outer diameter is greater than about 30 and the structure size allows, try to choose propane o-rings with a wire diameter of 3.55 to achieve larger The amount of compression and contact area.  

The materials of propane o-rings mainly include cyanide butadiene rubber NBR and fluorine rubber FKM, and fluorine rubber is more suitable for high temperature working conditions.

In addition to the material, an important indicator of the O-ring is its hardness, which is generally expressed by Shore hardness, ranging from 60 to 90. The larger the value, the higher the hardness. Under the same pressure, the higher the hardness, the stronger the ability to prevent extrusion (deformation or even tearing). Therefore, propane o-rings with higher hardness should be selected.

However, the common propane o-rings on the market are made of cyanide-butadiene rubber, and the Shore hardness is generally around 70, which is difficult to meet the requirements of a considerable part of the working conditions.

The groove design of the O-ring has related national standards, which are mainly divided into three types: dynamic seal, axial static seal and radial static seal. propane o-rings of flanges, box covers, etc. adopt axial compression to facilitate assembly and ensure sealing performance. In addition, the groove size standard in China's national standards has been lagging behind. For example, the outer diameter of the O-ring groove under internal pressure in the national standard is equal to the outer diameter of the O-ring, while the outer diameter of the O-ring groove of the PARKER flange joint Less than the outer diameter of the O-ring. When designing, reference should be made to foreign standards.

Flat sealant must not be used on the sealing surface with propane o-rings. A small amount of butter can be applied to the propane o-rings to prevent them from falling off. During maintenance, the O-ring specifications should be determined according to the groove size, not the thicker the wire diameter, the better.