We must first know life is a comprehensive index calculated values ??based on such factors as the choice of materials, pump mechanical seal manufacturers, processing methods and expected use conditions. Due to material defects, mechanical seal manufacturers, processing and use of uncertainty influence, and can not guarantee the life of each of the mechanical seal to reach consensus tandem double seal Due to the compact structure, chemical mechanical seal manufacturers, suitable for shaft diameter size small, small axial size, and the speed of larger middle loads of occasions. In the end is balanced mechanical seal,