【Daily Question: Pump Equipment】Weekly Summary March 31, 2019

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Monday (2019.3.25) https://bbs.hcbbs.com/thread-2446232-1-1.html 1. For a centrifugal pump impeller with twisted blades, the (back side) of the blades should be visible when looking at the impeller inlet； 2. The smaller the axial clearance on both sides of the vortex pump impeller, the higher the pump’s head can be. Tuesday (2019.3.26) https://bbs.hcbbs.com/thread-2492974-1-1.html The pump body of a horizontal centrifugal self-priming pump is in the shape of a large square box; what is its function? 1. Complete the basic functions of the centrifugal pump casing ； 2. The lower part of the pump body serves as a liquid storage chamber; after each shutdown, a certain amount of fluid remains in this chamber. Through the return holes at the bottom of the pump casing, this fluid flows back to the inlet of the impeller or to the outer diameter of the impeller, where it can be reused during the next start-up for self-priming purposes ； 3. The upper part of the pump body is the gas-liquid separation chamber, where the gas-liquid mixture is separated into gas and liquid; the gas is discharged through the outlet, while the liquid drops into the liquid storage chamber. Wednesday (2019.3.27) https://bbs.hcbbs.com/thread-2535228-1-1.html Multiple-choice question: The factors that affect the radial clearance of the impeller ring in a centrifugal pump are: ABCDE. A. Medium temperature ； B. Whether the medium contains particles ； C. Diameter of the mouth ring ； D. Whether the material between the stationary and moving mouth rings is prone to interlocking ； E. Viscosity of the medium ； Thursday (2019.3.28) https://bbs.hcbbs.com/thread-2569393-1-1.html For a positive displacement pump, with a medium specific gravity of 0.85 and a flow rate indicated on the pump’s nameplate of 15 L/s, the volumetric flow rate can be calculated as (15*3.6=54) m3/h, while the mass flow rate is (54*0.85=45.9) T/h. Friday (2019.3.29) https://bbs.hcbbs.com/thread-2572483-1-1.html 1. Among the various losses in centrifugal pumps, the volumetric loss gradually (decreases) as the flow rate increases ； 2. Rated parameters of the centrifugal pump: flow rate of 50 m3/h, head of 32 m, and rotational speed of 2900 r/min; therefore, the specific speed ns of this pump is (92.72). 1. Reduction in size (increased flow rate, lower head pressure, reduced pressure difference, decreased leakage at all return points, reduced volumetric loss, and improved volumetric efficiency) ； 2, 92.72 (ns = 3.65nQ^0.5/H^0.75; where ns is the specific speed) ； Q —— flow rate, m^3/s, ； H—— Head in meters ； n —— rotational speed, r/min). Saturday (2019.3.30) https://bbs.hcbbs.com/thread-2573372-1-1.html 1. Compared with single-screw pumps, double-screw pumps experience more severe wear between their screws. (Incorrect) 2. According to API610, unless the rotating and stationary ring gaskets have a Brinell hardness of 400 or higher on their wear-resistant surfaces, the difference in their Brinell hardnesses must be at least 50. (Well) Have a great weekend! !