What Should I Do if the Outlet Pressure of a Split Case Pump Drops?

Split case pumps are widely used in industrial, municipal, and commercial applications. A sudden drop in outlet pressure can affect system performance. This guide explains common causes and recommended corrective actions to restore normal pump operation.

1. Motor Reversal

Possible Cause: Wiring issues may cause the motor to rotate in the wrong direction.

Corrective Action: Always check the rotation direction before starting. If reversed, swap any two motor terminal wires.

2. Operating Point Shifts to High Flow and Low Head

Possible Cause: Reduced system backpressure causes the pump to operate in the low-head, high-flow region.

Corrective Action: Slightly close the discharge valve to restore normal pressure.

3. Pump Speed Reduction

Possible Cause: Pump head is proportional to the square of the speed; any speed drop reduces outlet pressure.

Corrective Action: Measure actual pump speed, find the cause, and restore the correct speed.

4. Inlet Cavitation

Possible Cause: Suction pressure below liquid vapor pressure causes cavitation.

Corrective Action: Check for blockages, ensure inlet valve is fully open, or raise suction tank liquid level.

5. Internal Leakage

Possible Cause: Excessive gap between rotating and stationary parts reduces discharge pressure.

Corrective Action: Inspect and repair/replace worn parts, such as impeller wear rings.

6. Impeller Flow Path Blockage

Possible Cause: Partial blockage hinders flow.

Corrective Action: Disassemble to remove debris; consider installing a suction strainer.

Conclusion:

Timely diagnosis and preventive maintenance are crucial. Regular inspections, correct installation, and adherence to manufacturer guidelines will help maintain optimal pump performance.