... Prevent return oil, Use for freezer,refrigerator etc Vaccum pump Character:1,Double high-speed direct coupling structure vane vacuum pumps2,Preparation special ... valve, prevent pump oil mix water and prolong pump oil use time, when opening gas ballast valve, still keep high limit vacuum3,Adopt ... Φ401.580706×236×3902XZ-25B6×10-225Φ50394786×276×470 Vaccum ring Vaccum line Vaccum pump