The reliable connection between the air leak tester and the tested object is the key prerequisite to ensure the accuracy of the test results. This process involves multiple links such as the selection of connection methods, the design of sealing structures, and the treatment of surface conditions, which need to be controlled from the details.
The reasonable selection of connection methods is the basis for achieving reliable connection. Different types of tested objects need to match the corresponding connection forms due to their differences in structural shapes, sizes and usage scenarios. For example, for tested objects with threaded interfaces, threaded connectors can be used for docking, and tight fit can be achieved through the screwing of threads; while for pipes or open-type components, flange connections or quick connectors are often used, and the contact surfaces are fit by the clamping mechanism. When selecting the connection method, the material and thickness of the tested object need to be considered to avoid deformation of the component due to excessive connection force, or leakage channels due to loose connection structures.
The design of the sealing structure directly affects the sealing of the connection. Common sealing components such as O-rings, sealing strips, etc., need to select appropriate materials and specifications according to the working environment and test pressure of the tested object. Silicone rubber seals are suitable for high temperature environments, while fluororubber is more suitable for oil-resistant occasions, and nitrile rubber performs well under normal pressure. The cross-sectional shape and compression amount of the sealing structure also need to be accurately calculated. Too large will increase the installation resistance, and too small will make it difficult to form an effective seal. For example, in the design of quick connectors, the conical sealing surface and the elastic sealing ring are often used to deform the sealing ring under axial pressure to fill the microscopic gap of the contact surface.
Pretreatment of the connection surface of the measured part is an important link that cannot be ignored. Impurities such as oil, rust, and dust on the surface will destroy the fit of the sealing surface and form a channel for gas leakage. Therefore, the surface of the measured part needs to be cleaned before connection. Solvent wiping, mechanical grinding or ultrasonic cleaning can be used to remove contaminants attached to the surface. For slight rust on the metal surface, sandpaper or grinding tools need to be used to polish until the bright base is exposed; if there are obvious scratches or pits on the surface, it should be repaired or replaced first to ensure the flatness and finish of the connection surface and provide a good foundation for sealing.
The operating specifications during the connection process are crucial to reliability. Taking threaded connection as an example, it is necessary to ensure that the threads are aligned during installation to avoid damage to the threads caused by forced screwing. You can manually pre-tighten until it cannot rotate, and then use a torque wrench to tighten it according to the specified torque, which can not only ensure the sealing effect, but also prevent the threads from slipping due to over-tightening. When connecting quick connectors, you need to pay attention to the insertion direction and force. Some connectors are equipped with guide structures, which need to be inserted smoothly along the axial direction. After hearing the "click" sound or feeling the locking feedback, perform pressure testing to avoid dislocation of the seal due to tilted insertion.
For special structures or special-shaped test pieces, special connection tooling needs to be customized. For example, for components with irregular curved surfaces, sealing tooling that adapts to their contours can be designed, and uniform compression can be achieved through elastic pressure plates or airbag structures. In the leakage test of automobile engine cylinder heads, customized sealing plugs and positioning brackets are often used. According to the hole distribution and surface shape of the cylinder head, they are accurately matched, which can not only ensure the synchronous connection of multiple test points, but also avoid leakage caused by insufficient adaptability of general fixtures.
The maintenance and care of the air leak tester connection port affects the long-term connection reliability. After long-term use, the sealing surface of the connection port may be worn and aged, such as the weakening of the spring elasticity of the quick connector and the deformation of the threaded connector. The port status needs to be checked regularly. When the seal is hardened or cracked, replace the accessories of the same specification in time; if there are scratches on the surface of the port, it can be lightly polished with fine sandpaper. In serious cases, it needs to be returned to the factory for repair or replacement. In addition, the port should be cleaned after each use to remove residual oil or metal debris to prevent impurities from accumulating and affecting the next connection.
In complex test scenarios, the impact of environmental factors on the connection must also be considered. In high temperature environments, seals are prone to softening and deformation, and high temperature resistant materials need to be selected and the clamping force needs to be adjusted appropriately; in low temperature environments, the elasticity of the material decreases, and the temperature can be maintained by preheating the connection parts or using a heating sleeve. In vibration situations, the connection structure may leak due to looseness. Anti-loosening devices can be added, such as anti-loosening nuts for threaded connections and locking clamps for quick connectors to ensure that the connection remains stable in a dynamic environment. Only by comprehensively considering the influencing factors of each link in the connection can a reliable connection between the air leak tester and the test piece be achieved, providing an accurate basis for leak detection.
