Double seal machinery disassembling is convenient, in does not move in decelerator's situation, machine seals may take out by the whole. The balance tank will provide the compression to seal the fluid, causes machine to seal in the cavity room the pressure to be higher than the cauldron internal pressure, guarantees the reliable sealing property.Suitable pressure scope from entire vacuum to 340kg/cm2. Machine seals the housing to have cools the clamp cover, is suitable the high temperature operation.