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Inspection and Maintenance of Shielded Pumps 2.1 Daily Inspection ① Check whether there are any abnormalities in the pointer of the outlet pressure gauge; ② Verify whether the current level is within normal limits or if it is abnormally high; ③ Look for any unusual noises or vibrations; ④ Ensure that the bearing monitoring indicator remains within the red range; ⑤ Monitor the temperature of various components of the pump; ⑥ Check for any liquid leaks. Shielded pumps are primarily used for transporting toxic, flammable and explosive, highly corrosive, radioactive, and valuable liquids; therefore, a large number of such pumps are employed in the organic chemical industry. Cage pumps are relatively expensive, and their maintenance is an important task. This article discusses, based on practical experience, how to carry out the daily maintenance of shielded pumps. 1 Structure and principle of the canned pump 2.2 Bearing monitor The bearing monitor is used primarily to detect corrosion of the shielding sleeve and wear of the bearings. When the pointer of the monitor indicates the red area, it means that the contacts of the monitor have broken, and high-pressure argon gas is leaking from within the monitor – this situation is caused by excessive wear of the bearings. In such cases, it is necessary to replace the monitor, the shielding sleeve, the thrust plate, the bearings, and the eccentric nut, with costs ranging from 2,600 to 2,850 yuan. If the machine continues to operate for a long time after the pointer reaches the red area, it will inevitably lead to wear of the impeller, or damage to the motor due to wear of the stator shielding sleeve and the rotor shielding sleeve. The repair costs in such cases are generally between 20,000 and 30,000 yuan. The working principle of the shielded pump is the same as that of a regular centrifugal pump; the difference lies in the drive motor. The motor of the shielded pump is completely enclosed within a second layer of isolation sleeve or shielding sleeve, with leakage prevention relying primarily on the internal corrosion-resistant shielding sleeve. The shielding sleeve is sealed by welding to ensure that the stator windings and rotor core do not come into contact with the working fluid. Shielded pumps do not require oil for lubrication; their bearings are lubricated by the circulation of the fluid they operate with. This means that the central shaft is hollow, allowing for the return flow of the lubricating fluid.