The dynamic sealing structure of the pump can be divided into packing seal, mechanical seal, dynamic seal and floating ring seal :
1. The structure of packing seal, the sealing principle is to use the packing gland stuffing packing into the stuffing box, make contact with the outer surface of the pump shaft or sleeve and the inner surface of filler to block the liquid in the pump axial external leakage. Packing has the advantages of simple structure, convenient replacement, but the packing and the shaft or shaft direct friction, the packing too tight, the friction force is greater, the greater the power consumption, and easy to burn packing; if the packing too loose, then the pump in fluid leakage. Moreover, for the delivery of solid materials containing the pump, the filler is worn or loose will lead to slurry leakage, resulting in pump shaft wear, pollution bearing. Therefore, the packing seal is only used in the operation environment and leakage requirements are not high occasion.
2. Mechanical seals (also known as end face seal) refers to the two rings by the sealing element, in the vertical axis of the smooth and straight surface of the mutual fit, and make the relative rotation of the sealing device. Compared to the packing seal, mechanical seal structure, reliability, safety, service life, maintenance cycle, power loss and so on have improved. The structure of mechanical seal than the seal packing complex, machining accuracy (verticality, face runout etc.) the demand is higher, and the need to install some technology. At present, the type of mechanical seal is very rich, the user can according to the characteristics of the pump operating environment requires special design, in order to achieve good sealing effect.
3. Dynamic seal generally refers to the application of the Deputy impeller in the solid liquid pump seal, or deputy blade of a joint dynamic seal impeller. The fluid dynamic seal system combined with a blade of deputy vice impeller dynamic seals or pump, usually cover impeller pump (including front and rear) on the outside surface of the blade (or of blade), vice impeller, rotary sheet and parking sealing etc.. The liquid in the pump shaft is driven by the centrifugal force acting on the liquid in the impeller and the auxiliary blade, and the water pressure generated by the water pressure blocks the high pressure fluid from the main impeller outlet. When designing, the fluid pressure in the gap between the pump shaft and the pump casing is required to be close to the external pressure of the pump. Dynamic seals should be used in combination with mechanical seals or packing seals to ensure that the sealing device can effectively block the leakage of liquid when the pump stops running.
