... non--sealing 2.self --control 3.self --priming pump Features:Property:WFB series non - sealing self - control and self - priming pump, ... centrifugal sealing device", which get rid of traditional filling seals, packing seals, mechanical seal, thoroughly overcome " running, emitting, ... control valve", achieves "once - priming, life - long self - priming."4.Small vibration, low noise, flexible move, ...