What happens when the centrifugal pump rotates in reverse direction?

1. Potential Damage:
   1. Loosening of Impeller: In some pump designs, particularly those with threaded impellers, reverse rotation can cause the impeller to loosen and detach from the shaft, potentially causing catastrophic damage to the pump housing.
   2. Improper blade angles: The impeller blades are designed to efficiently push fluid outwards during normal rotation. The angle of the blades is crucial for this function. When rotating in reverse, the fluid encounters these blades at angles they are not designed for. This creates uneven forces acting on different parts of each blade.
2. Difficult to Detect: Unlike a positive displacement pump where the flow would completely reverse, a centrifugal pump might still move some fluid even when running backwards. This makes it more challenging to diagnose reverse rotation without monitoring tools or by observing a significant drop in pump performance.
3. Performance:

Running a Forward Impeller in Reverse:

Before diving into the consequences of rotating forward curved impeller in reverse rotation, let us know the fundamental characteristics of forward curved impeller.
https://amechieneer.com/types-of-centrifugal-fans/#1-forward-curved-blade

Consequences of rotating the forward curved impeller in the reverse direction.

• As indicated in the provided hyperlink, the forward-curved blade is specifically designed to produce exceptionally high flow rates when all impellers are rotating at the same speeds, surpassing the performance of radial and backward-curved blades. It can be deduced that when a forward-curved blade rotates in the opposite direction, its characteristics transform, resembling those of a backward-curved blade and consequently leading to reduced flow rates.
• As highlighted in the provided hyperlink, it’s evident that the blade length of a forward-curved blade is comparatively shorter than that of radial and backward blades. The blade length plays a crucial role in efficiently converting kinetic energy into fluid pressure. Therefore, when the forward-curved blade rotates in the opposite direction, the shorter blade length results in a diminished ability to generate pressure, leading to pressures lower than the rated values.