When the vacuum pump is working, air bubbles always cause bubbles, especially when there are active additives in the oil, and the foam is not easy to disappear. The use of foam in smooth oil will destroy the oil film, not only cause the friction surface to attack or increase wear, but also cause the oxidation of smooth oil to undergo metamorphosis. The gas in the operating vacuum system is discharged from time to time in the sealed vacuum pump oil layer. The discharged gas will generate a large number of bubbles on the surface of the oil layer and overflow from the exhaust hole of the vacuum pump, resulting in oil loss and equipment pollution. The pump oil with anti foaming agent has made obvious progress in anti foaming effect. Confirmation of seals: (1) Confirm whether the installed seal is the same as the required model. (2) Before installation, carefully compare with the general assembly drawing to see if the number of parts is correct. (3) For mechanical seals with parallel coil spring drive, the spring can be divided into left and right rotation, which must be selected according to the rotation direction of the rotating shaft.