【Daily Question: Pump Equipment】Weekly Summary 2019.3.17

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Monday (2019.3.11) https://bbs.hcbbs.com/thread-2345883-1-1.html There are three units for measuring vibration values of testing equipment: (mm), (mm/s), and (mm/s2). Vibration is evaluated based on three parameters: displacement, velocity, and acceleration. The most commonly used unit for vibration is (mm/s). Tuesday, 2019.3.12: https://bbs.hcbbs.com/thread-2346864-1-1.html. Briefly explain why, in long-distance pipeline transportation, a larger pipe diameter results in a higher economic flow velocity (Please explain based on the principles, without considering cost control.) Answer: Due to the viscosity of the liquid, the resistance that prevents its flow mainly comes from friction against the pipe walls. The greater the distance from the wall, the greater the resistance; the magnitude of this resistance decreases gradually as the distance from the wall increases. In pipes with a larger diameter, there is more liquid at a greater distance from the walls, so the resistance causing deceleration is smaller. Therefore, the economic flow velocity is higher for larger pipe diameters. Wednesday (2019.3.13) https://bbs.hcbbs.com/thread-2347898-1-1.html For a given pump: 1. When the pump’s speed increases, the pump’s net positive suction head will (increase) ； 2. After the pump speed increases, the vibration value considered acceptable according to the vibration standards will (increase). Thursday (2019.3.14) https://bbs.hcbbs.com/thread-2349232-1-1.html Briefly describe the function of the pump cover in a single-stage cantilever centrifugal pump (OH1) 1. Connected to the pump body, and together with it forms the pressure housing ； 2. Forms an shaft seal chamber together with the shaft (or shaft sleeve), used for installing and fixing the shaft seal ； 3. Establish a connection with the bearing suspension (in some cases, the pump cover is held in place between the bearing suspension and the pump body), thereby fixing the bearing suspension ； 4. Forms the water cooling chamber of the pump cover, cools the shaft seal, and prevents heat from being transferred toward the bearings ； 5. Install the fixed pump cover ring, which is used in conjunction with the rear ring of the impeller (it also creates a small gap with the impeller blades) to balance the axial forces. 6. Implement the P01 flushing scheme. Friday (2019.3.15) https://bbs.hcbbs.com/thread-2350216-1-1.html 1. Ordinary explosion-proof motors should be used in areas with an altitude of no more than 2000 meters (Incorrect) ； 2. The motor mounting type commonly used for vertical pipeline pumps is B5 (incorrect). Saturday (2019.3.16) https://bbs.hcbbs.com/thread-2351134-1-1.html 1. When selecting a pump, the choice of material for the pump’s flow-through components is related to whether the medium contains particles (correct) ； 2. Stop valves are not used to regulate flow at the pump outlet (correct). Happy weekend!