Precautions for Shutting-down & Switching Split Case Pump

Proper shutdown and switching procedures for a split case pump are essential for maintaining system reliability, preventing equipment damage, and ensuring operator safety. The following guidelines cover standard and emergency operations.

Shutdown of the Split Case Pump

1. Gradually close the discharge valve until the flow rate reaches the minimum flow requirement.

2. Disconnect the power supply to stop the split case pump, then close the outlet valve.

3. If a minimum flow bypass pipeline is installed, ensure the bypass valve is fully open before closing the discharge valve, then cut power and stop the pump. For high-temperature split case pumps, allow the temperature to drop below 80°C before stopping the circulating water. The seal system (such as flushing fluid or sealing gas) should be stopped approximately 20 minutes after pump shutdown, depending on the condition.

4. For standby split case pumps: Keep the suction valve fully open and the discharge valve fully closed. If a minimum flow line is present, ensure the bypass valve remains fully open. Maintain suction pressure and continue supplying cooling water. Lubrication oil level should be monitored closely, especially in winter to avoid freezing. Keep heating and cooling systems functional.

5. Rotate the standby pump periodically as required to prevent shaft seizing.

6. For pumps scheduled for maintenance: After the pump is shut down and cooled, first close the nitrogen inlet valve of the dry gas seal system, depressurize the seal chamber, and then drain the pump and cooling systems completely. Ensure internal pressure is released to zero. Purge any residual material, close all valves, and isolate power by notifying the substation. All field procedures must comply with HSE (Health, Safety, and Environmental) standards.

Split Case Pump Switching

When switching split case pumps, it is critical to maintain stable system pressure and flow. Avoid sudden flow surges or system depressurization.

Normal Switching Procedure

1. Ensure the standby split case pump is fully prepared for operation.

2. Open the suction valve of the standby pump. Fill the pump and expel any trapped air, then start the standby pump following the standard startup procedure.

3. Monitor the standby pump’s outlet pressure, motor current, vibration, leakage, and temperature. If all parameters are normal, gradually open the discharge valve of the standby pump while simultaneously closing the discharge valve of the running pump to keep system pressure and flow constant.

4. Once the standby pump’s pressure and flow are within design values, completely close the discharge valve of the original pump, cut its power supply, and mark it as stopped.

Emergency Switching Procedure

Emergency switching is required in case of critical failures such as oil spray, motor fire, or major pump damage.

1. Confirm the standby split case pump is ready for operation.

2. Immediately disconnect the power supply of the failed pump and stop its operation. Start the standby pump without delay.

3. Open the discharge valve of the standby pump to achieve the required outlet pressure and flow.

4. Close the suction and discharge valves of the failed pump and proceed with emergency response actions.

Conclusion

Following proper shutdown and switching procedures is essential for protecting the split case pump, maintaining stable system performance, and ensuring operator safety. By adhering to standard and emergency guidelines, you can reduce equipment wear, prevent failures, and ensure reliable long-term operation.