Sewage pump impeller forms and respective characteristics

Like other pumps, the impeller and the pressure chamber are the two core components of the 

sewage pump. Its performance also represents the performance of the pump. The anti-clogging 

performance, efficiency, and cavitation performance of the sewage pump. The anti-abrasion 

performance is mainly guaranteed by the two major components of the vane pump and the pressurized water chamber.

Impeller structure type: The structure of the impeller is divided into four categories: blade type 

(open type, closed type), swirl type, flow channel type, (including single flow channel and double flow 

channel) spiral centrifugal type.

1. The open and semi-open impeller is easy to manufacture. When there is a blockage in the impeller,

 it can be easily cleaned and repaired. However, in long-term operation, the abrasion of particles will 

increase the gap between the blades and the side wall of the pressure water chamber, thus reducing 

the efficiency. And the increase in the gap will destroy the pressure difference distribution on the blades.

 Not only does it produce a large amount of vortex loss, but it also increases the axial force of the pump. 

At the same time, due to the increased gap, the stability of the flow pattern of the liquid in the flow channel

 is destroyed, causing the pump to vibrate. This type of impeller is not easy to transport media containing

 large particles and long fibers. In terms of performance, this type of impeller has low efficiency. The maximum

 efficiency is about 92% of that of an ordinary closed impeller, and the lift curve is relatively flat.

2. Swirl impeller: Pumps using this type of impeller are partially or completely retracted away from the flow 

path of the pressurized water chamber. Therefore, it has good non-clogging performance, strong particle 

passing ability and long fiber passing ability. The flow of particles in the pressurized water chamber is driven

 by the vortex generated by the rotation of the impeller. The suspended particles themselves do not generate

 energy, but only exchange energy with the liquid in the flow channel. During the flow process, suspended 

particles or long fibers do not come into contact with the blades. The blades are subject to minor wear and 

tear, and there is no increase in gaps due to abrasion. This will not cause a serious drop in efficiency during

 long-term operation. Pumps using this type of impeller are suitable for pumping media containing large

 particles and long fibers. In terms of performance, the efficiency of this impeller is low, only equivalent to 

about 70% of that of an ordinary closed impeller, and the lift curve is relatively flat.

3. Closed impeller: This type of impeller has higher normal efficiency. And the situation is relatively stable in

 long-term operation. The axial force of the pump using this type of impeller is small, and auxiliary blades 

can be installed on the front and rear cover plates. The secondary blades on the front cover can reduce the 

vortex loss at the impeller inlet and the wear of the sealing ring by particles. The secondary blades on the 

rear cover not only balance the axial force, but also prevent suspended particles from entering the mechanical 

seal cavity and protect the mechanical seal. However, this type of impeller has poor non-blocking properties

 and is easy to wind, making it unsuitable for pumping untreated sewage media containing large particles (long fibers).

4. Flow channel impeller: This type of impeller is a bladeless impeller. The impeller flow channel is a curved 

flow channel from the inlet to the outlet. Therefore, it is suitable for pumping media containing large particles 

and long fibers. Good blocking resistance. In terms of performance, the efficiency of this type of impeller is

 similar to that of ordinary closed impellers, but the lift curve of the pump with this type of impeller drops 

steeply. The power curve is relatively stable and it is not easy to cause overpower problems. However, the

 cavitation performance of this type of impeller is not as good as that of ordinary closed impellers, and it is 

especially suitable for use in pumps with pressure inlets.

5. Spiral centrifugal impeller: The blades of this type of impeller are twisted spiral blades that extend axially 

from the suction port on the tapered hub body. This type of impeller pump has the functions of both a positive

 displacement pump and a centrifugal pump. When suspended particles flow through the blades, they do not

 hit any part of the pump, so they are non-destructive. Less destructive to conveyed objects. Due to the propulsion

 effect of the spiral, suspended particles have strong passability, so pumps using this type of impeller are suitable 

for pumping media containing large particles and long fibers, as well as high-concentration media. It has obvious 

characteristics in situations where there are strict requirements on the damage of the conveying medium.