Hello everyone, I am Xiaobian. Do you know the sealing ring? Today Xiaobian will analyze it for you in detail, hoping to help you.

O-rings are the most commonly used seals. However, due to improper selection, groove design, processing and assembly, oil leakage often occurs, which can be described as a small thing causing a big problem.

The standards for O-ring sizes in my country's national standards include GB1235-76, GB3452.1-88 and GB3452.1-92. Among them, the O-ring cross-sectional diameter (also known as wire diameter) specified in GB1235-76 is 1.9, 2.4, 3.1, 3.5, 5.7, etc. The O-ring adopts the marking method of "outer diameter × wire diameter", which is generally called the old national standard; GB3452.1-82 is basically the same as GB3452.1-92, which is generally called the new national standard. It specifies O-ring cross-sectional diameters of 1.8, 2.65, 3.55, 5.3, etc. The new national standard adopts international practice, and the O-ring adopts the marking method of "inner diameter × wire diameter".

When choosing O-rings, first try to choose the new national standard. The wire diameters of 2.65 and 3.55 are the most commonly used. When the outer diameter is greater than about 30 and the structural dimensions allow, try to choose O-rings with a wire diameter of 3.55 to achieve greater compression and contact area.

The materials of O-rings are mainly nitrile rubber NBR and fluororubber FKM. Fluororubber is more suitable for high temperature conditions.

In addition to the material, an important indicator of O-rings is its hardness, which is generally expressed in 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, O-rings with higher hardness should be selected.

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