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This post was last edited by 3983596_FPPZ on 2019-6-9 at 13:42. Monday (2019.6.3): https://bbs.hcbbs.com/thread-2719543-1-1.html 1. Fill in the blank: On a given system, when the pump flow rate increases, the system’s net positive suction head will (decrease)； 2. Judgment: Rigid couplings do not compensate for the positional errors between the two shafts nor provide vibration damping (correct). Tuesday (2019.6.4) https://bbs.hcbbs.com/thread-2720229-1-1.html 1. 1 standard atmosphere equals the pressure generated by a height of 760 centimeters of mercury (incorrect) ； 2. The shoulder mark on the pump cover, ф215h6, indicates that the basic dimension is a diameter of 215 mm; the tolerance zone falls in the h category (with no upper deviation), and the width of the tolerance zone corresponds to the precision level of 6. (Correct) Wednesday (2019.6.5) https://bbs.hcbbs.com/thread-2721587-1-1.html 1. Judgment: For large-scale equipment, when checking the rotation direction of the motor, it is necessary to disconnect the coupling and then start the motor individually to verify whether its rotation direction matches that indicated on the nameplate. (Correct) 2. Selection: According to the pump vibration standard GB/T29531-2013, pump vibrations are classified into four levels: A, B, C, and D. When the pump’s vibration is at level (C), it indicates that the pump can only operate for a short period of time, with strict monitoring of its operating conditions required ； A, Grade A B, Grade B C, Grade C D, Grade D Thursday (2019.6.6) https://bbs.hcbbs.com/thread-2722127-1-1.html 1. The flow rate under normal operating conditions for this pump is indicated as “0.05 t/s”, and the specific gravity of the medium is 1.13; therefore, the required flow rate for this pump should be (159.3) m3/h ； 2. Internal defects in the casting materials of pump pressure-bearing parts are commonly detected using PT, where PT refers to inspection by the liquid penetration/dyeing method. Friday (2019.6.7) https://bbs.hcbbs.com/thread-2723731-1-1.html College Entrance Exam Day/Dragon Boat Festival 1. Fill in the blank: When the head of the centrifugal pump is 110 meters, the specific gravity of the fluid is 0.93, and the absolute pressure at the inlet is 0.34 MPA, then the gauge pressure at the outlet is (1.26) MPA ； 2. Judgment: The longer the motor takes to start, the lower its starting current. (Correct – there is a dispute here; to be announced.) Saturday (2019.6.8) https://bbs.hcbbs.com/thread-2724009-1-1.html On the day of the college entrance examination: 1. In normal cavitation, cavitation always occurs first at the inlet of the first impeller in multi-stage centrifugal pumps (Correct) ； 2. The finer the inlet pipeline of a self-priming pump, the stronger its self-priming capacity (incorrect). Happy weekend! ! ! College entrance exam day!!