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Monday (2018.12.31) https://bbs.hcbbs.com/thread-2238671-1-1.html 1. In our country, the higher failure rate of equipment in winter compared to summer is mainly due to the low temperatures in winter. (True) 2. The function of a reducing pipe is to enable a smooth transition in area between pipes of different diameters. (True) Tuesday (2019.1.1) https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=2239542&page=1&extra=#pid21554045 I took a day off for New Year’s Day, haha... Wednesday (2019.1.2) https://bbs.hcbbs.com/thread-2240821-1-1.html 1. The mechanism for balancing the axial force of a pump: Similar to a balance disk, it has an axial clearance, so it can automatically adjust and balance the axial thrust when the pump shaft moves axially. (False) 2. The greater the deviation of the pump’s flow rate from the design value, the greater the radial force on the impeller. (True) Thursday (2019.1.3) https://bbs.hcbbs.com/thread-2242216-1-1.html 1. There are three most common reasons for excessive vibration in pumps: operating the pump far away from its optimal operating point or having cavitation tendencies, poor fixation of the base and piping supports, and improper alignment of the couplings. (True) 2. Like high-speed pumps, multi-stage pumps should have their outlet valves slightly opened at startup, in order to prevent excessive heating due to vigorous mixing inside the pump and to allow any gas formed by the vaporization of the fluid to escape. (True) Friday (2019.1.4) https://bbs.hcbbs.com/thread-2248182-1-1.html 1. Compared to plum blossom-shaped elastic rubber (claw-type) couplings, diaphragm couplings have greater compensatory capacity, but their temperature resistance is lower. (False) 2. The reason why centrifugal pumps can only transport liquids and not gases is that liquids have a higher density; they are subjected to greater centrifugal force due to the rotation of the impeller, which enables sufficient negative pressure to be created at the inlet, allowing liquid to continuously flow into the pump’s inlet. (Yes) Saturday (2019.1.5) https://bbs.hcbbs.com/thread-2249684-1-1.html 1. The greater the absolute difference between the pH value of the medium transported by the pump and 7, the stronger the corrosiveness of that medium (Wrong). 2. The shorter the inlet pipe of a centrifugal pump, the better; therefore, elbows should be connected directly to the pump inlet (Wrong)