The Theoretical Basis of Face Contact Pressure Design of the Zero-Leakage Mechanical Seal

The value of face contact pressure has an important influence on the wear life and leakage rate of the mechanical seal. For a long time, people have chosen face contact pressure based on experience and lack of theoretical support, which greatly reduces the effectiveness of the mechanical seal. Based on the percolation theory, the critical porosity of zero-leakage at the wetting and non-wetting sealing interface working in liquid medium is first discussed. The influence of end-face frictional heat on end-face friction and wear is then investigated. The design criteria for the face contact pressure of mechanical seals with zero-leakage and long-life operation are established. Afterwards, the face contact pressure range of the mechanical seal working in conventional different liquid medium is calculated, and the influence of different working conditions on the face contact pressure range change is analyzed. Existing studies have shown that mechanical seals can achieve zero-leakage and long-life operation. Under the rotating and stationary rings’ physical parameters and given working conditions, the face contact pressure range of the sealing medium water and propane propylene is 0.477~1.132 MPa. The diesel sealing medium has a larger face contact pressure range than that of water and propane propylene, which can reach 0.477~2.183 MPa. The working condition speed, medium temperature, and medium pressure have an influence on the face contact pressure range, while the influence of the working condition speed is the most significant.