Question

8. A 10-inch model pump delivering water at 180°F at 800gal/min and 2500 rpm begins to cavitate when the inlet pressure and velocity are 14 psia and 22 ft/s, respectively. Determine the required NPSH for (i) the model and (ii) a prototype which is 5 times larger and runs at 1000 rpm (Hint: Watch "Chapter 12-NPSH.mp4")

Answer 1

some these are Ft3 1600 tables for the given problem of pump (model & prototype) water is flowing at 180F at which water bas properties as follows 8.g 60.6 Ubf values taken from standard Pu psfa and a bit approximated it begins to cauitate when inlet pressure ☺ 14 psla and velocity NPSH be written as for model for above condition (NPSH) m = Pi-Pv f.g ag given that 22 ft/s رة can + (14x144) 1600 + (22)2 (2 X 32.2) 60.6 ( 14x144 is inlet press. in psfa) + 7.516 6.865 Answer (NPSH)m - 14.38 At

For s times larger the given prototype which rpm and suns at np TODO NPSH given 2 (NPSH), (NASH)m (money on De 2 14.38 1000 2500 Answer . 57:52 ft U (NPSH),
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