The 240-mm-diameter pump represented in Fig.12.6 (attached below) is used to mov
ID: 1843730 • Letter: T
Question
The 240-mm-diameter pump represented in Fig.12.6 (attached below) is used to move water in a piping system whose demand curve is 60 + 270Q 2 , where Q is in m3 /s. Find the discharge, required input power, and the NPSH requirement for:
(a) One pump
(b) Two pumps in parallel
100 TTTTTTTTTTTTT TTTTTTTTTTTTTT TTTTT TTTTTTTm 260 40 50 60 75 80 240 75 220 Outer diameter 70 40 of impeller (mm) 10 100 240 Wp (kw) 50 12 205 10 NPSH (m) 6 240 50 100 150 200 250 300 3500 400 Fig. 12.6 Radial-flow pump and performance curves for four different impellers with N 2900 rpm (ex 304 rads). Water at 20°C is the pumped liquid. (Courtesy of Sulzer Pumps Ltd.)Explanation / Answer
a) From first graph, we get discharge Q
Q = 610 gal/min
Required input power = 40 KW
610 gal/min = 138.546 m3/hr.
NPSH = 3.9 m
b) For two pumps in parallel, discharge becomes,
Q= 2*610 = 1220 gal/min
Required input power = 58 KW
1220 gal/min = 277.0921 m3/hr.
NPSH = 7.6 m
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