Croos Pump (Shanghai) Co., Ltd.

The Structure of the Sewage Pump

The impeller

The sewage pump is the same as other pumps, the impeller, the pressurized water chamber, the two core components of the sewage pump. Its performance represents the performance of the pump. The anti-clogging performance of the sewage pump, the high and low efficiency, and the cavitation performance are mainly guaranteed by the two main parts of the vane pump and the pressurized water chamber. Here's an introduction:

Type of impeller structure

The structure of impeller is divided into four categories: vane type (open type, closed), swirling type, runner type, (including single runner and double channel) spiral centrifugal type four kinds.

Open-type semi-open impeller makes it easy to clean and repair when the impeller is blocked. But in the long run, the friction between the blades and the wall of the pressure water will be increased, which will reduce the efficiency. And the increase of clearance can damage the pressure distribution on the blade. Not only produces a lot of vortex loss, but also increases the axial force of the pump, at the same time, due to the increased clearance, the stability of the liquid in the flow state is destroyed, causing the pump to vibrate. This type impeller is not easy to convey medium with large particles and long fibers. In terms of performance, the type impeller is inefficient and the maximum efficiency is about 92% of the normal closed impeller, and the lift curve is relatively flat.

The swirl impeller

The pump of this type impeller is used, because the impeller part or all of the shrinkage pressure water chamber flow. Therefore, the non-plugging performance is good, and the ability of passing the particle and the long fiber is stronger. The particles in the pressurized water flow are driven by eddy currents generated by the rotation of the impeller, and the suspended particles themselves do not generate energy, but only exchange energy in the flow channel and liquid. In the process of flow, the suspended particles or long fibers are not in contact with the blade, the blade is more abrasive and there is no gap due to the erosion. In the long run, it will not cause the problem of serious decrease in efficiency. The pump of this type impeller is suitable for pumping medium with large particles and long fibers.

In terms of performance, the impeller is less efficient, which is only about 70% of the normal closed impeller, and the lift curve is relatively flat.

The shrouded impeller

The impeller of this type is more efficient. And in the long run, the condition is more stable, the pump axial force of this type impeller is smaller, and the auxiliary blade can be set on the front and back cover. The auxiliary blades on the front cover can reduce the vortex loss of impeller inlet and the wear of the particles to the seal ring. The auxiliary blade on the back cover plate not only plays a balanced axial force, but also prevents the suspension particles from entering the mechanical seal chamber to protect the mechanical seal. But the type impeller is not obstructive, it is easy to be wound and not to be used to extract the medium containing large particles (long fibers).

The flow passage impeller

The impeller is a leafless impeller, and impeller is a curved flow from the inlet to the outlet. Therefore, it is suitable to extract medium containing large particles and long fibers. It id good anti-blocking.

In terms of performance, the impeller efficiency of the type impeller is not different from that of the normal closed impeller, but the lift curve of this type impeller pump is relatively steep. The power curve is relatively stable, which is not easy to produce super power problem, but the cavitation performance of the impeller is not as good as the normal closed impeller, especially suitable for the pump with pressure inlet.

The spiral centrifugal impeller:

The blade of this impeller is a twisted spiral blade, which extends from the suction inlet along the axis of the cone wheel hub. The pump of this type impeller has the function of volumetric pump and centrifugal pump. The suspended particles flow out of the blade and not impinge any part of the pump, so it is not damaged.It is less destructive to the conveyor. Because of the propulsion of spiral, the passing of aerosol particles is strong, so the pump of this type impeller is suitable for pumping medium with large particles and long fiber, as well as high concentration of media. In the case of the destruction of conveying medium, it has obvious characteristics.

In terms of performance, the pump has a steep lift curve and the power curve is flat.

The spiral casing

The water pressure chamber used in the sewage pump is the most common in the volute, and the radial guide or runner blade is used in the submersible pump. The volute has three kinds of spiral, ring and mediating type. Helical volute is basically not in the sewage pump. The circular pressurized water chamber is easy to be used in small sewage pumps because of its simple structure. However, the application scope of the annular pressure chamber is gradually smaller due to the intermediate (semi-spiral) pressure water chamber. Due to the intermediate pressure water chamber and the high permeability of the spiral water chamber, more and more attention has been paid to manufacturers.

In conclusion, any series of sewage pumps is only a combination of different types of impeller and different types of pressurized water chamber according to the requirements of conveying medium and installation. As long as the impeller and pressure water chamber can optimize the configuration. The performance of the pump is guaranteed. (of course, you can't ignore the design and manufacture of other parts.) 
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