Centrifugal pump casing and shaft seal device The role of the pump casing is to seal the impeller in a certain space, in order to impeller suction and out of the liquid. Pump casing made of spiral shape, it is also known as the volute. Due to the gradual enlargement of the cross-sectional area of ​​the flow passage, the high-speed liquid thrown out from the impeller gradually reduces the flow velocity and effectively converts part of the kinetic energy into static pressure energy. Pump housing not only brings together the liquid thrown by the impeller, but also an energy conversion device. The function of the shaft sealing device is to prevent the liquid in the pump casing from leaking out of the shaft or outside air into the pump casing. Common shaft seal packing seal and mechanical seal two. Fillers are generally impregnated with oil or asbestos rope coated with graphite. The main purpose of the mechanical seal is to achieve the purpose of sealing by the relative movement between the moving ring mounted on the shaft and the stationary ring fixed on the pump casing.