Practical Exercise 1 on Purification Technology [003]

1. Contact the upstream and downstream stations to prepare for shutting down the pump; 2. Slowly close the outlet valve of the centrifugal pump; 3. Press the stop button, and after the pump has stopped running, close the inlet valve to drain the liquid from the pump and cut off the power supply; 4. Collect the tools and equipment. Clean up the site and keep operation records

　(1) First, close the pump outlet valve, then stop the pump to prevent it from reversing. 　　(2) When stopping the pump, pay attention to the deceleration of the shaft; if this process takes too little time, check whether there is any grinding or sticking inside the pump. 　　(3) If it is a hot oil pump, stop the flushing oil or seal oil first, and open the balance or connection valve of the inlet pipeline to prevent the inlet and outlet pipelines from freezing and cracking. 　　(4) If the pump needs repair and the inlet valve is also closed, it should be determined whether to purge and depressurize based on the nature of the repair work; if there is pressure inside the pump, it may be due to the inlet and outlet valves not being sealed properly.

① Close the pump outlet valve. ② Stop the motor. ③ The cooling water can be turned off after the cold oil pump stops operating. ④ For a pump that is to be repaired, it is necessary to close the inlet and outlet valves, and open the drain valve to remove the liquid and residual pressure from within the pump. While draining the liquid from the pump, it is absolutely forbidden to stop the cooling water flow to prevent the cooling water system from freezing and cracking. ⑤ Pumps that have been out of use for an extended period should be turned over once a day to prevent the shaft from bending

① Close the pump outlet valve. ② Stop the motor. ③ The cooling water can be turned off after the cold oil pump stops operating. ④ For a pump that is to be repaired, it is necessary to close the inlet and outlet valves, and open the drain valve to remove the liquid and residual pressure from within the pump. While draining the liquid from the pump, it is absolutely forbidden to stop the cooling water flow to prevent the cooling water system from freezing and cracking. ⑤ Pumps that have been out of use for an extended period should be turned over once a day to prevent the shaft from bending

① Close the pump outlet valve. ② Stop the motor. ③ The cooling water can be turned off after the cold oil pump stops operating. ④ For a pump that is to be repaired, it is necessary to close the inlet and outlet valves, and open the drain valve to remove the liquid and residual pressure from within the pump. While draining the liquid from the pump, it is absolutely forbidden to stop the cooling water flow to prevent the cooling water system from freezing and cracking. ⑤ Pumps that have been out of use for an extended period should be turned over once a day to prevent the shaft from bending

1. Stop the pump upon receiving a notification from the control room. 2. Open the minimum return valve. 3. Gradually close the outlet valve. 4. Press the pump’s stop button to shut it down, and then close the minimum return valve. 5. Inform the control room that the pump has been stopped

1. Slowly close the pump outlet valve； 2. Turn off the power supply ； 3. Close the pump inlet valve.

(1) When shutting down a centrifugal pump, the outlet valve should be closed first to prevent backflow of pressurized water from the outlet pipe into the pump in case the check valve fails, which could cause the impeller to rotate in the reverse direction and lead to pump damage. (2) Stop the pump by pressing the stop button

(1) Close the outlet valve, then the motor. (2) After the hot oil pump is shut down, reduce the flow rate of cooling water, close the seal oil valve, and then open the outlet valve (or open the preheating valve if one is available) to carry out preheating, so that the pump is in a hot standby state. (3) The amount of oil used during preheating should not be excessive, to prevent the impeller from rotating in reverse ； If the pump running causes evacuation, preheating should be stopped; evacuate first and then proceed with preheating. (4) After the pump to be inspected is shut down, close the inlet and outlet valves. Once the temperature has dropped to an appropriate level, relieve the pressure by venting (be especially careful at this time to ensure that the pump’s inlet and outlet valves are properly closed and there is no internal leakage; address any issues that arise promptly). (5) After shutting down the pump in winter, it is necessary to maintain a small flow of cooling water, and slightly open the cross-connected manual valves at the inlet and outlet of the standby pump to allow circulation of the fluid and prevent the pipelines from freezing and getting blocked.

First, close the outlet valve and press the stop button; after the pump stops, close the inlet valve, drain the liquid from the pump, and cut off the power supply