【Daily Question: Pump Equipment】Weekly Summary, 4/21/2019

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This post was last edited by 3983596_FPPZ on 2019-4-21 09:20. bg3.png Monday (2019.4.15): https://bbs.hcbbs.com/thread-2673575-1-1.html. The centrifugal pump has a flow rate of 230 T/h, a medium specific gravity of 1.05, a head of 36 m, an efficiency at the operating point of 73%, and a rotational speed of 2950 rpm; therefore, the shaft power of the pump is (30.9) KW, while the power required for the motor is (37) KW. Tuesday (2019.4.16) https://bbs.hcbbs.com/thread-2674474-1-1.html 1. In magnetic pump and shielded pump systems that do not feature a torque ring structure, the rotation speed of the impeller is the same as that of the motor rotor (correct) ； 2. All pipe threads have sealing capability (incorrect). Wednesday (2019.4.17) https://bbs.hcbbs.com/thread-2675436-1-1.html Motors used in high-power equipment (**standardly, those with a power rating of over 75KW) are often started using voltage reduction or soft start methods. Please briefly explain the advantages of such starting methods 1. During full-voltage starting, the motor’s starting current is 7–10 times the rated current. This method of starting can reduce the impact on the power grid and electrical equipment ； 2. During full-pressure starting, the rotational components of the equipment possess a certain amount of inertia as well as pre-load from the medium, which results in the highest torque value during the starting process. This starting method helps to reduce damage to the torque-transmitting elements of the equipment (such as couplings, shafts, hubs, keys, etc.). Thursday (2019.4.18) https://bbs.hcbbs.com/thread-2676421-1-1.html 1. The forces and moments acting on the pump’s outlet piping can act on the pump’s inlet and outlet ports up to a certain limit (correct) ； 2. The motor housing must be properly grounded before it can be used normally (correct). Friday (2019.4.19) https://bbs.hcbbs.com/thread-2677223-1-1.html 1. API610 stipulates that in order to allow for the removal and maintenance of internal pump components without having to remove the inlet piping, pump body, or motor, the shaft distance between the motor and the pump shaft must be at least (125) mm for centrifugal pumps other than those of the OH series; 2. API610 requires that for pumps ordered under specific specifications, measures such as replacing the impeller with one of larger diameter should be taken to increase the head by at least (5%) . Saturday (2019.4.20) https://bbs.hcbbs.com/thread-2678132-1-1.html 1. An overcurrent in the motor must be caused by the pump it drives (incorrect) ； 2. Sliding vane pumps belong to the category of vane-type centrifugal pumps (incorrect). Wish all sailors a pleasant weekend! !