SEAL OF IMPURITY PUMP

Seal of impurity pump has always been a problem puzzling people, and this problem becomes more and more serious with the enlargement of the scope of use of impurity pump. The solid particles transported by the impurity pump become larger and larger, and the harmfulness of the liquid becomes more and more serious. These substances corrode and wear the shaft and seal more seriously than ordinary sediment.

Principle of Pump Seal

The pump seal between the rotating pump shaft and the fixed pump body is abbreviated as the shaft seal. The function of shaft seal is to prevent high pressure liquid from leaking out of pump and air entering pump. Although the shaft seal occupies a small position in the pump, the normal operation of the pump is closely related to the shaft seal. Therefore, the shaft seal structure must be selected reasonably to ensure the safe operation of the pump.

Form of Pump Seal

The shaft seal of impurity pump mainly includes the following categories: gland packing, mechanical seal, floating ring seal, other seals, etc.

Gland packing: Gland packing is the most commonly used seal mechanism in general pumps. It consists of packing ring, packing sleeve, packing, packing gland, long button stud and nut. Through the contact between the packing and the surface of the pump shaft, it prevents the medium from passing through to achieve the purpose of sealing. There are many small gaps and grooves between the contacting sealing surfaces. Therefore, applying enough pressing force to achieve the necessary sealing ratio can make the packing produce elastic-plastic deformation to reduce the gap.

Mechanical seal: Mechanical seal is achieved by the end faces of two precision machined moving rings and static rings which are contacted by springs along the axial direction. In mechanical seal, the moving ring and the static ring are the main sealing elements. The moving ring and the static ring are generally made of different wear-resistant materials, such as graphite, ceramics, tungsten carbide, silicon nitride, chrome steel, etc.

The structure of floating ring seal is simpler than that of mechanical seal. The performance of floating ring seal is reliable, but its axial dimension is slightly larger than that of other seals. The floating ring seal uses the contact between the end face of the floating ring and the end face of the floating sleeve to realize the axial seal.

Other seals: Small pump seal is used in large pump. The large pump has a large volume, so the structure of shaft seal increases correspondingly. The increase of the volume of parts will affect the processing difficulty of all parts of the pump, thus affecting the form and position tolerance and accuracy of parts. In terms of sealing, the difficulty is greater than that of small and medium pump. When the liquid in the large pump leaks out, a small pump can be added at the shaft seal of the large pump to drain the leaking liquid. In addition to the above several seals, spring seal, elastomer bellows seal, non contacting mechanical seal can also be used.