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  • Reverse rotation of the centrifugal pump impeller effect?

    Hussein Barakat

    Member

    Updated: Oct 26, 2024
    Views: 3.4K

    effect of reversing the centrifugal pump impeller rotation ????

    What will happen if we reverse rotation of the centrifugal pump impeller [c.w] <===> [c.c.w]?
    And the effect on head [pressure] and discharge?

    Answer:

    Centrifugal pumps are designed to operate in a specific direction, usually clockwise (CW) or counterclockwise (CCW) when viewed from the drive end. This direction affects the design of the pump impeller and casing, and the pump's overall efficiency and performance.

    If you reverse the direction of rotation of a centrifugal pump impeller, several effects are likely to occur:

    1. Reduced Efficiency: The pump's overall efficiency will be significantly reduced. This is because the impeller blades and pump casing are designed for a specific direction of flow, which matches the direction of rotation.

    2. Decreased Head and Discharge: The pump's head (pressure) and discharge (flow rate) will both decrease. This happens because the water is not being pushed through the pump as effectively when the impeller rotates in the opposite direction. This can lead to decreased pump performance and possible damage to the pump due to increased internal loads.

    3. Increased Cavitation: Cavitation is a phenomenon where vapor bubbles form in a liquid and then suddenly collapse, producing shock waves. This can occur when the pressure of the liquid falls below its vapor pressure. Reversing the impeller direction can increase the likelihood of cavitation, which can cause serious damage to the pump components over time.

    4. Increased Wear and Tear: Since the pump components are not designed to handle the reversed flow, there will be increased wear and tear on the pump. This can lead to premature pump failure and increased maintenance costs.

    5. Motor Overload: The pump motor may be overloaded due to the increased strain, potentially causing motor failure.

    In general, reversing the rotation of a centrifugal pump impeller is not recommended unless the pump is specifically designed to handle bidirectional flow. Always consult with the pump manufacturer or a qualified engineer before making any significant changes to a pump's operation.

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  • Rohan_sK

    Member • Jan 9, 2010

    There is a big difference between the terms "Reverse Rotation" and "Reverse Flow" related to the Centrifugal Pump.

    Reverse Rotation means that the direction of the rotation of the Impeller is reversed. This may be caused by the reversal of the direction of the driving motor by the reversing of the wiring connections.

    In this case there will be no difference in the Operation of the Pump principally. That means the Pump would still continue to deliver the fluid from the low pressure suction side to the Higher Pressure Delivery side in the positive direction of flow.

    But the fact is that the flow would not be generating the flow characteisitcs and parameters according to the original design. The flow would certainly be forward directed but there will be jamming in the flow and pressure heads would drastically change affecting the discharge.

    This is actually happenig because of the original design of the Invollute Casing of the pump and the location of the Discharge tube. The Volute casing and Discharge tube are designed and located according to " the Direction Of Rotation Of the Pump" which is pre determined for a particular design.

    The Impeller type used ( open flow, closed, mixed type) and the Volute Casing designed as per the original pump specifications will be responsible for the actual type of discrepancy in the pressure head and the flow characteristic observed and will vary from pump to pump.

    But certainly the changed flow pattern ( though forward directed) will reduce the efficiency and cause bubbling etc. in the flow chamber eventually affecting the eficiency of the pump and reducing the discharge. There may be cavitation observed in the larger sections of the volute chamber and the pressure head will be affected accordingly.

    But as far as the Basic Pumping action is considered the Pump would still continue to pump the fluid in the Positive Discharge Direction.
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  • Hussein Barakat

    Member • Jan 9, 2010

    Thanks [Rohan_sK], yes i meant "Reverse Rotation"
    Thanks again ....... 😀
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  • vibhor_one

    Member • Jan 16, 2010

    nothing more required roshank nice explaination....
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  • paw1

    Member • Mar 26, 2010

    Hi, (new here)

    Just one question, why, while designing the impeller, was the direction of rotation (relative to the involute) chosen as it is? It obviously has to have some advantage over designing the pump for a reverse rotation.
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  • Mahesh Prakash Palav

    Member • Aug 19, 2015

    thank u so much sir.......
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