Before starting the centrifugal pump

(1) Pre-startup preparations a. Pre-startup inspection: Check whether the name, model, key properties, and quantity of lubricant meet the requirements specified in the technical documents； Are the bearing lubrication system, sealing system, and cooling system in good condition? Are the oil and water pathways of the bearings unobstructed? ； Rotate the rotor of the pump 1–2 times to check for any friction or sticking ； Are there any objects that could interfere with rotation near the coupling or in areas such as belt guards? ； Are the foundation bolts of the pump, bearing housing, and motor loose? ； The valves or auxiliary devices in the pump’s operating system should be in the position that results in the lowest load when the pump is running; the outlet control valve should be closed ； Start the pump manually to check whether the rotation direction of the impeller matches the designed direction. If it does not, the impeller must be brought to a complete stop first; only after adjusting the motor wiring can the pump be started again. b. Fluid filling: Before starting the pump, the pump casing and suction pipe must first be filled with the material, as an air presence prevents the vacuum at the pump’s suction inlet from being created and maintained. c. Heat pump: A pump used to transport high-temperature liquids; for example, the boiler feed water pump in power plants must be warmed up before it is started. This is because when the feed water pump starts, high-temperature feed water flows through the pump, causing the pump’s temperature to rise rapidly from room temperature to 100–200°C. This creates a temperature difference between the inside and outside of the pump as well as between its various components. If there isn’t enough time for heat transfer and no appropriate measures are taken to control the temperature rise, uneven expansion throughout the pump will occur, leading to deformation, wear, vibration, and even bearing failure in different parts of the pump. (2) Startup procedure: The pump chamber and suction pipe of the centrifugal pump must be completely filled with water without any air, and the outlet valve should be closed (if the pump operates at high pressure and high flow rates, the outlet valve should be opened to about one-quarter). Heating pump operation completed. For pumps with forced lubrication, start the oil pump to supply oil to each bearing. Start the cooling water pump or open the cooling water valve. Start the pump by closing the switch; after startup, the pump should not run idly for more than 2–4 minutes. Once the speed reaches the rated value, gradually open the outlet valve of the centrifugal pump to increase the flow rate and reach the required load. (3) Precautions during operation: Pump manufacturers specify limits for bearing temperatures. The temperature rise of rolling bearings should generally not exceed 40°C, and the surface temperature should not exceed 70°C; otherwise, it indicates a problem inside the rolling bearings, and the machine should be stopped for inspection. If it continues to operate, it may cause an accident. For the temperature specifications of sliding bearings, refer to the technical documents related to the pump; the handling method is the same as that for rolling bearings.

The inlet valve is fully open and the outlet valve is fully closed to reduce the starting current.

LBP’s answer is the most comprehensive. In simple terms: 1. Turn the disk； 2. Prime the pump before starting ； 3. After the inlet valve is fully open and the outlet valve is fully closed, slightly open it back a bit (based on experience) ； 4. Start ； 5. Monitor the outlet pressure and pump current to adjust the valve position of the outlet valve; the specific adjustment amount depends on the process requirements for these two parameters. The above views are purely personal opinions; please let me know where you reside!

The key is to have the inlet valve of the pump fully open and the outlet valve fully closed

The inlet valve is fully open and the outlet valve is fully closed to reduce the starting current and prevent the motor from being damaged.

The inlet valve is fully open and the outlet valve is fully closed to reduce the starting current. It also depends on whether it is a positive pressure pump or a negative pressure pump. With a positive-pressure pump, water can flow in directly; whereas a negative-pressure pump requires water to be poured in or a vacuum to be created in order to draw water upward. The circuit system also needs to be checked before starting.

Brother, I’m extremely grateful here! Thank you all for your answers!

Before starting the centrifugal pump, the inlet valve should be fully opened, the outlet valve should be fully closed, and it is necessary to ensure that the pump chamber is filled with liquid to prevent air locking. Before starting the motor, it is also necessary to ensure that the ground bolts are tightened, remove any debris, and verify that the water cooling system, lubrication system, etc., are functioning properly.

Before starting the centrifugal pump, the inlet valve should be fully opened, the outlet valve should be fully closed, and it is necessary to ensure that the pump chamber is filled with liquid to prevent air locking.

It seems that the inspection of the entire process pipeline, as well as the level of liquid in the pump inlet tower or tank, is still missing

Initial state: (P) The pump is filled with process medium. (P) It is confirmed that the coupling has been properly installed. (P) It is confirmed that the protective cover is in place. (P) The mechanical, instrumentation, and electrical aspects of the pump have been checked and are in order. (P) The pump rotates smoothly and evenly. (P) The inlet filter of the pump is clean and properly installed. (P) It is confirmed that cooling water is supplied to the pump. (P) It is confirmed that the lubrication system meets the requirements. (P) It is confirmed that the oil level in the bearing housing is normal. (P) It is confirmed that the lubrication pump is in good condition and ready for use (for centrifugal pumps with forced lubrication). (P) It is confirmed that the inlet valve of the pump is open. (P) It is confirmed that the outlet valve of the pump is closed. (P) It is confirmed that the motor switch of the pump is in the off or stopped position. (P) It is confirmed that power is supplied to the motor. 1. Preparation to start the centrifugal pump: (P) It is confirmed that the pressure gauge is properly installed; then the pressure gauge is put into use. 1.1 Activate the auxiliary systems. 1.1.1 Activate the cooling water system: Open the cooling water supply valves and drain valves (for the bearing housing, pump body, and oil cooler). (P) Confirm that the return flow is unobstructed. 1.1.2 Activate the lubrication system (for centrifugal pumps with forced lubrication): Confirm that the oil level in the lubrication tank is normal; start the lubrication pump; fill the filter and oil cooler with oil and remove any air from them. (P) Confirm that the oil circuit is unobstructed. (P) Confirm that the lubrication oil pressure is normal. (P) Confirm that the temperature of the lubrication oil is normal. 2. Filling the centrifugal pump (see Level C, 2). 2.1 For pumps operating at normal temperatures: Open the pump’s vent valve to release air. (P) Confirm that air release is complete; then close the vent valve. Rotate the pump. 2.2 For pumps operating at high temperatures: Slightly open the inlet valve; open the vent valve to release air. (P) Confirm that air release is complete; then close the vent valve. Rotate the pump by 180º every half hour. Open the valve controlling the heating rate of the pump so that the temperature rises at a rate of ≤50°C per hour. (P) Confirm that the temperature difference between the pump body and the process medium is less than 50°C. Close the valve controlling heating. Fully open the pump’s inlet valve. 2.3 For liquefied gas pumps: Slightly open the vent valve to release air, then close it. Use steam or water to heat the seal gland. (P) Confirm that the temperature of the seal gland is at least 40°C. Rotate the pump. (P) Confirm that there are no leaks

There’s no need to make it complicated. Generally, before starting the pump, perform inspections, turn the pump shaft by hand, supply cooling water, fully open the inlet valve, open the plug valve at the outlet pressure gauge, and release air until liquid starts to flow out; then close the plug valve. Open the outlet valve to 10–15%, and finally power on the pump – adjusting the water pressure at the outlet will suffice