1.non--sealing 2.self --control 3.self --priming pump Features:Property:WFB series non - sealing self - control and self - priming pump, fills ... 3.Transplant working principle of vacuum pump, stable and reliable self - suction performance, in particular, the adoption of " ... air control valve", achieves "once - priming, life - long self - priming."4.Small vibration, low noise, flexible move, simple ...