1.non--sealing 2.self --control 3.self --priming pump Features:Property:WFB series non - sealing self - control and self - priming pump, fills ... air control valve", achieves "once - priming, life - long self - priming."4.Small vibration, low noise, flexible move, simple ... selected).B - level working condition: as continuously running, two of the three parameters can meet the requirement.C - ...