Impeller structure type

The structure of impellers can be divided into four categories: blade type (open, closed), swirl type, channel type, (including single channel and double channel) spiral centrifugal type.
The manufacturing of open and semi open impellers is convenient. When blockage occurs inside the impeller, it can be easily cleaned and repaired. However, in long-term operation, the wear and tear of particles can increase the gap between the blades and the sidewall of the pressurized water chamber, thereby reducing efficiency. And increasing the gap will damage the pressure difference distribution on the blade. Not only does it generate a large amount of vortex losses, but it also increases the axial force of the pump. At the same time, due to the increase in clearance, the stability of the liquid flow state in the flow channel is damaged, 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, with the highest efficiency being about 92% of that of a regular closed impeller, and the head curve is relatively flat.
Swirl impeller
A pump using this type of impeller may experience partial or complete separation of the impeller from the pressurized water chamber flow channel. So it has good non blocking performance, strong ability to pass through particles and long fibers. The particles flow in the pressurized water chamber and are propelled by the eddy currents generated by the rotation of the impeller. 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, and the wear of the blades is relatively light. There is no situation where the gap increases due to erosion, and it will not cause a serious decrease in efficiency during long-term operation. The pump using this type of impeller is suitable for pumping media containing large particles and long fibers.
In terms of performance, the efficiency of this impeller is relatively low, only about 70% of that of a regular closed impeller, and the head curve is relatively flat.
Closed impeller
This type of impeller has a higher normal efficiency. And in long-term operation, the situation is relatively stable. The axial force of the pump using this type of impeller is relatively small, and auxiliary blades can be set on the front and rear cover plates. The auxiliary blades on the front cover plate can reduce the vortex loss at the impeller inlet and the wear of particles on the sealing ring. The auxiliary blades on the rear cover plate not only balance the axial force, but also prevent suspended particles from entering the mechanical seal chamber and provide protection for the mechanical seal. However, this type of impeller has poor blockage free performance, is easy to entangle, and is not suitable for pumping untreated sewage media containing large particles (long fibers).