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Preparations before testing centrifugal pumps (including vortex pumps and gear pumps): (1) Check the finishing of the foundation; it should meet the requirements； Check the foundation bolts; they should be tightened properly ； The alignment accuracy of the two axes meets the specified requirements. (2) The rotation direction of the motor should be the same as that of the pump ； The insulation of the motor shall meet the specified requirements ； The turning gear should operate smoothly without any abnormal phenomena. (3) Electrical instruments, as well as the pressure gauges and vacuum gauges of pumps, should be sensitive and accurate, while valves should be flexible and reliable. (4) For centrifugal pumps that transport liquids at temperatures above 120°C, cooling of the bearing area is necessary to ensure reliable lubrication of the bearings. (5) Mechanical seals should be cooled and flushed, and used for transporting materials that tend to crystallize. Before the pump is restarted, the crystalline deposits in the seal area must be removed to avoid affecting the sealing performance or damaging the seal surfaces ； The assembly of mechanical seals shall comply with the specified requirements. (6) For pumps equipped with packing seals, the tightness of the packing should be appropriate ； The coolant seal ring should be aligned with the coolant pipe opening, and the coolant flow should be unobstructed. Load testing: (1) The requirements for filling, purging, and venting the pump shall be carried out in accordance with the provisions of the technical documents. (2) Before starting positive displacement pumps such as reciprocating pumps and screw pumps, the inlet and outlet valves must be opened first ； When starting a centrifugal pump, the inlet valve should be opened first and the outlet valve closed; the starting power of the motor will not be very high ； Once the outlet pressure stabilizes, slowly open the outlet valve immediately to adjust the desired flow rate and head. When the outlet valve is closed, the pump should not operate continuously for too long, otherwise the liquid inside the pump will heat up due to agitation by the impeller. (3) Open the exhaust valve to fill the entire pump body with liquid; once it is full, the centrifugal pump must close the exhaust valve ； Start the pump in jog mode, and ensure the rotation direction is correct before initiating full operation. (4) For pumps that permit trial operation using water as the medium, it is safest to conduct the test with water. For pumps used for transporting oil products, where the pump chamber is connected to the bearings and the working medium is used as a lubricant, the trial operation should be carried out using that working medium. (5) The pump must undergo a single-unit test run at its rated load for 2–4 hours continuously ； The vortex pump and gear pump should be tested under no-load conditions (with the outlet valve fully open) for a minimum of 15 minutes ； After normal operation, conduct segmented operation tests at 1/4, 1/2, and 3/4 of the operating pressure ； The operating time for each period should be no less than 0.5 hours ； Finally, operate continuously under work pressure for more than 2–4 hours ； Testing at the next pressure level should not be carried out until testing at the previous pressure level is successful. (6) Before trial operation, high-temperature pumps must be preheated. The temperature difference between the pump body surface and the inlet process pipeline containing the working medium should not exceed 40°C℃ ； When preheating the pump body, the temperature should rise evenly, with an increase of no more than 50 per hour℃ ； During the preheating process, crank the shaft half a turn every 10 minutes (WeChat account: Pump Manager) ； When the temperature exceeds 150°C, turn the shaft half a turn every 5 minutes ； Check the axial expansion clearance at the bolts on the sliding end of the pump housing base ； Open the inlet valve and the vent valve to release the gas inside the pump; after preheating to the specified temperature, close the vent valve ； During the trial operation shutdown, the pump should be rotated half a turn every 20–30 minutes until its temperature drops to 50°C. (7) Check the anchor bolts to ensure they are not loose ； The rotor and all moving components are operating normally, with no abnormal noises or friction ； The auxiliary systems should operate properly, and the pipe connections should be secure with no leaks. (8) The temperature of sliding bearings should generally not exceed 70℃ ； The pump runs continuously for 2 hours under rated conditions. (9) To stop the centrifugal pump, gradually close the outlet pipeline valve, cut off the power supply, and close the inlet valve. For vortex pumps and gear pumps, the outlet valve should be closed after the power supply is cut off. Preparations before testing a magnetic pump: (1) Check that all fixed connections are secure and not loose; rotate the external magnetic coupling by hand to verify that there is no rubbing. (2) All valves and instruments on the pipeline have been installed, and they have been purged, cleaned, and tested successfully. Load testing: (1) Operation without a load is strictly prohibited; it is not allowed to transport media containing solid particles. The transported media must not contain ferromagnetic or hard impurities, nor may it operate at a flow rate lower than 30% of the rated value. (2) Before starting the pump, open the inlet valve to fill the pump with the liquid to be transported. (3) Close the outlet valve; operate the electric motor in jog mode to check whether the pump is rotating in the correct direction. (4) After the pump starts, the outlet valve should be opened slowly; once the pump is operating normally, the outlet valve can then be adjusted to the desired opening degree. Run it for 5–10 minutes; if there are no abnormalities, it can be put into operation. (5) Check whether the current, temperature rise, and outlet pressure are normal, whether there is any leakage during operation, whether the operation is stable, and whether vibration and noise are within normal limits. (6) Shutdown procedure: Close the outlet valve; cut off the power supply; close the inlet. When the pump will not be used for an extended period, clean the flow channels inside the pump and cut off the power supply. Preparations before testing the vacuum unit: (1) Open the cooling water inlet valve and check whether the cooling water flow is unobstructed. (2) The external shaft seal cavity and oil cup should be filled with lubricating oil, while the lubricating oil in the gearbox and bearing housing should be filled to 3/4 of the height of the oil sight glass. No. 1 vacuum pump oil should be used as the lubricating oil. (3) Appropriate measures must be taken in the following situations: a. When there is dust or particles in the gas being drawn in, a dust collector or filter should be installed before the intake ； b. If the inhaled gas is corrosive, neutralization measures must be taken ； c. If the intake gas contains water vapor and the pump selected is an oil-sealed mechanical pump, such a pump should be equipped with a gas trap; when there is an excessive amount of water vapor, a condenser must be installed. Load test: (1) Start the primary pump; (2) Open the valves on the pre-evacuation bypass pipeline of the primary pump as well as the valves on the inlet and outlet pipelines of the Roots vacuum pump. (3) Once the pressure inside the system reaches the inlet pressure allowed by the Roots vacuum pump, close the valve on the bypass pipe, and then start the Roots vacuum pump. If there is no bypass pipe or valve, the Roots vacuum pump can be started once the system pressure reaches the allowable value. In the case of an automatic control device, the starting process can be automated. (4) Depending on the actual conditions of the vacuum system, if it is a relatively small sealed system, the Roots vacuum pump can be started after starting the pre-pump. In the case of larger vacuum systems, although rotary vane vacuum pumps equipped with relief valves provide overload protection, for economic reasons, it is advisable to start the rotary vane vacuum pump only after the pre-stage pump has reached a certain pressure level. (5) Shut off the mechanical pump gas trap valve of the preceding stage during shutdown (if the gas trap valve of the preceding stage is in the open position while in use). Next, close the inlet valve of the Roots vacuum pump, shut down the mechanical booster pump stage by stage, and finally turn off the pre-stage pump; it is strictly forbidden to follow the wrong sequence for shutting down the equipment ； While stopping the upstream pump, immediately bleed air from the inlet of the upstream pump and close the cooling water inlet valve ； If it needs to be out of use for an extended period, or to prevent cracking in winter, the remaining water in the cooling water jacket must be drained. Points to note during operation: (1) During operation, the Roots vacuum pump must be used strictly in accordance with its technical specifications. Under normal circumstances, the inlet pressure of the Roots vacuum pump should be below 1330 Pa; its maximum allowable inlet pressure must not be exceeded. If this limit is exceeded, the ZJP Roots vacuum pump equipped with a relief valve can provide automatic protection; however, this protection applies only to overloading of the motor. If operated for a long time at a pressure exceeding the maximum allowable inlet pressure, the pump may also fail due to overheating. (2) Pay attention to the motor load and the temperature rise in various parts of the pump; under normal operating conditions, the maximum temperature rise of the pump shall not exceed 40°C. The maximum temperature must not exceed 80°C. (3) There should be no irregular abnormal vibrations during operation. (4) If motor overload, excessive temperature rise, abnormal noises, or severe vibration are detected during operation, the machine should be stopped immediately to investigate the cause and resolve the fault. Preparations before testing a multi-stage pump: (1) Check the maintenance records; the quality of the maintenance work should meet the requirements of the relevant maintenance procedures, and it is necessary to ensure that the records are complete and the data is accurate. (2) Check the lubrication condition; if it does not meet the requirements, replace it or add lubricant promptly. (3) The cooling water system should be unobstructed. (4) The turning of the shaft is smooth with no unevenness, no abnormal noises, and the packing gland is not skewed. (5) Before starting the hot oil pump, it is necessary to warm up the pump, with the preheating rate not exceeding 50°C per hour. Load test: After completing the no-load test and confirming that all performance parameters of the multi-stage pump meet the technical requirements, a load test can be carried out. The steps for the load test are as follows: Rotate the pump shaft and turn on the cooling water. Pumping pump. Start the motor. Pay close attention to the pump’s outlet pressure, motor current, and operating condition. Slowly open the outlet valve of the multistage pump until normal flow is achieved. Use a control valve or pump outlet valve to regulate flow and pressure. The load test shall meet the following requirements. (1) It operates smoothly without noise, and the lubrication and cooling systems are functioning properly. (2) The flow rate and pressure are stable, reaching the capacity indicated on the nameplate or the determined capacity. (3) At the rated head and flow rate, the motor current does not exceed the rated value. (4) Temperatures in all areas are normal. (5) Bearing vibration amplitude: When the operating speed is 1500 r/min or less, it should be no less than 0.09 mm ； When the operating speed is below 3000 r/min, it should be no less than 0.06 mm. (6) There are no leaks at any joints or connected pipelines. (7) The shaft seal leakage shall not exceed the following standards. Packing seal: For general liquids, 20 drops/minute ； Heavy oil, 10 drops/minute. Mechanical seal: For general liquids, 10 drops/minute ； Heavy oil, 5 drops/minute. Disclaimer: This article is reproduced from the Internet; the copyright belongs to the original author.