Abstract: Internal leakage is a typical failure mode for cut-off valves. It is necessary to evaluate the seal reliability under various stress conditions. There are several types of sealing pairs for cut-off valves. One of them is conical type, which is line contact initially and becomes surface contact while the material endures deformation with contact pressure when the valve is closed for the first time. The contact pressure of the sealing pair may drop or even the contact surfaces separate when the valve is loaded with excessive external force, leading to internal leakage. In this study, a cut-off valve of air conditioners is taken as example. Techniques are adopted to promote convergence such as meshing control, Arbitrary Lagrangian-Eulerian (ALE) adaptive meshing, and adding a little damping to the sealing pair. The sealing status is judged according to contact status and contact pressure distribution. The reason of internal leakage is analyzed according to the plastic strain distribution of the valve seat and its structure is strengthened.

Key words: Cut-off valve, Sealing, Leakage, Contact pressure, Contact status