Question

A 6.5-in pump, running at 3500 rpm, has the measured performance for water. If this pump is rescaled in water to require 20 hp for break horsepower input at BEP point while running at 3000 rpm, determine the appropriate (a) impeller diameter; (b) flow rate; and (c) efficiency for this new condition. 50 100 150 200 250 400 450 Q, gal/min: H, ft: 201 200 194 189 156 300 350 181 169 80 81 198 64 139 72 29 50 77 79 74 n, %:

Answer 1

Solution ft 6uagem Giren Datar Accreding to from the table value, flow rate iar 350 gollmin e 350x BEP_head (H) € 169.ft 191 Step 1- * Calculated input (BEP) hoepasser. Formulae: We know that, po fxgxQx 2 81 0.81 Where Specs fe gowity (Y)- eg 4 = 62.4 lbf ft? Now Substitute from 3 po , (624) x (350) x (119) 0.81 8220 400 po 2 ft x lloffs 981 po 10148-64% thp 550ft.1bf po 5 18.45 hp

step &:- laly Calculate impeller Diameter:- It was required to diameter with speed of rotation CRPM). We know that formulae, pl Р exnx (D)5 Plon) 3x (05) 2 from Substitute Equation { " Where e-1.94 20 X 550 ft. lbfls top (1.94) x (300x boys x(05)" 10148.64 2 (1394) x(3500 x 63 xf65x1.** 18 30 0.04536 10148.64 17955.94 (05)1

(05) 0.565196 . (0.565 565196)15 D' - 7.434 in. Step 3!- (6) flow rate of New condition: We have know that formulare: * new (previous 3 nnew e D 13 Mpreulousx Opruious O newt 200 xL x17.434x! 4x 60 3 - Ifts 350gpn x 7350 44900m 3500 * 16.5x 1 ) X 60

Qnew 0-77951 1.18875 9.27071 Grew 0.99535 x TUT ft als 446 gal new calawate News Cogdition of efficiency:- In diameter and impellen of previous the values assume the maximum efficiency of running pump Formulas y Of_condition =[D & Drew] => Now efficiency of neo Condition. = 81% Hence proved the Soulton.