Abstract: Aiming at the serious leakage and frequent overhaul of the mechanical seal in the liquid-ring vacuum pump, this paper puts forward the modification scheme of transforming the seal form into double-end dry gas seal through analyzing the existing problems of the mechanical seal. It introduces the basic structure and operation principles of the dry gas seal, points out the precautions for use. The transformed dry gas seal and auxiliary control system have been used in the liquid-ring vacuum pump successfully. After long-running verification, the problems of the original seal have been solved. The dry gas seal has no medium leakage and the maintenance is simple. Thus the overhaul times are greatly reduced and the service life of the seal is prolonged. The safety and stability of the equipment operation are greatly improved as well.

Key words: liquid-ring vacuum pump, dry gas seal, double-end face, mechanical seal