The sealing structure design of the air tightness test bench plays a decisive role in accurately measuring the leakage rate, and there is a close and complex relationship between the two.
First, the material selection of the sealing structure is one of the key factors. Different materials have different sealing properties. For example, rubber materials are often used for sealing due to their good elasticity and plasticity. For high-pressure environments, high-strength, high-pressure resistant rubber materials may need to be selected; while in special gas environments, the chemical stability of the material should be considered to prevent the reaction with the test gas and cause the seal to fail, thereby affecting the measurement accuracy of the leakage rate.
Secondly, the form of the sealing structure is crucial. Common ones include O-ring seals and lip seals. O-ring seals rely on their extrusion deformation in the groove to fill the sealing gap. When the sealing surface is processed with high precision and installed properly, the leakage rate can be effectively reduced. Lip seals can better prevent gas leakage under a certain pressure through the close fit between the lip and the sealing surface, and are especially suitable for sealing parts with relative movement. Different sealing forms have different performances in controlling the leakage rate under different working conditions.
Furthermore, the processing accuracy of the sealing surface directly affects the leakage rate. If the sealing surface is rough, even if high-quality sealing structures and materials are used, gas may still leak along microscopic uneven areas. High-precision sealing surface processing can reduce such microscopic leakage channels and reduce leakage rates. For example, through grinding, polishing and other processes, the sealing surface can achieve a higher degree of finish and enhance the sealing effect.
The installation method of the sealing structure should not be ignored. Correct installation ensures that the seal is evenly compressed and gives full play to its sealing performance. Improper installation, such as twisting, excessive stretching or compression of the seal, will destroy its sealing integrity and increase the leakage rate. In the design, it should be considered to provide structures and guides that facilitate accurate installation.
In addition, temperature changes have a significant impact on the sealing structure and leakage rate. Increases or decreases in temperature will change the elastic modulus, expansion coefficient, etc. of the sealing material, thereby changing the sealing performance. In high temperature environments, sealing materials may become soft and aged, reducing the sealing effect; at low temperatures, they may become hard and brittle, and microcracks may appear, causing leakage. Therefore, the design of the sealing structure needs to consider temperature compensation or select materials that can adapt to a wide temperature range.
The durability of the sealing structure is closely related to the change of the leakage rate over time. As the test bench is used, the seals will gradually wear and age, and the leakage rate may gradually increase. The service life of the sealing structure should be estimated during design to facilitate regular maintenance and replacement to ensure that the leakage rate of the test bench is always within an acceptable range during long-term use.
All aspects of the sealing structure design of the air tightness test bench are inextricably linked to the leakage rate. Only by comprehensively considering these factors can an efficient and accurate sealing structure be designed to ensure the reliable operation and accurate measurement of the air tightness test bench.
