Centrifugal Pump Selection and Sizing - Calgary Pump Symposium ...

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Suction Specific Speed (Nss) - a ‘dimensionless’ parameter describing impeller eye geometry - evaluated at BEP, max diameter - Nss = rpm x gpm^0.5 / NPSHr^0.75 , use ½ Q for double suction impeller - consider this example: 500 gpm pump at 3550 rpm - Nss = 9,000 when NPSHr = 18.2 ft - Nss = 11,000 when NPSHr = 13.9 ft - Nss = 13,000 when NPSHr = 11.2 ft - for the same pump, lower NPSHr achieved by one or more of: - sharpening the impeller inlet edges - increasing the impeller inlet area by: decreasing # of blades; and /or, increasing blade inlet angle; and /or, increasing inlet area 26
Suction Specific Speed (Nss) - Guidelines - typical range is 7,000 to 16,000 (and higher) - higher Nss results in restricted range of acceptable operation - for pumps with Ns 500 –1800, max Nss up to 11,000 is acceptable - for pumps with Ns 1,800 – 2,400, max acceptable Nss should be reduced to about 9,000 - pumps with Ns above 2,400 should be avoided 27
Page 1 and 2: Centrifugal Pump Selection and Sizi
Page 3 and 4: Pump types - Vertical In-line Pump
Page 5 and 6: Pump types - Between-Bearing Pump (
Page 7 and 8: Pump Selection - Old School 7
Page 9 and 10: The Goal • We want to select and
Page 11 and 12: Pump Selection - order of preferenc
Page 13 and 14: Relative Costs - example 1 • 200
Page 15 and 16: Relative Costs - example 3 • 200
Page 17 and 18: Overhung Pumps - Typical Coverage P
Page 19 and 20: VIL Pumps - Typical Limits • Tip
Page 21 and 22: VIL Pumps: Rigidly-coupled (OH4) ty
Page 23: Specific Speed (Ns) - a ‘dimensio
Page 28 and 29: Minimum Flow • Minimum flow issue
Page 30 and 31: Limited Range at Higher Nss Suction
Page 32 and 33: Head ( ft) 500 450 400 350 300 250
Page 34 and 35: Equations & Correlations • Head,
Page 36 and 37: Required Information • Require th
Page 38 and 39: Typical Casing Sizes Pump Speed Q (
Page 41 and 42: Worked Example: H= 500 ft, Q= 4500
Page 43: Overhung Pumps - Typical Coverage P
Page 46: Worked Example: H= 380 ft, Q= 1750
Page 49 and 50: Buying Pumps - Marrying the Hydraul
Page 51 and 52: Pump Standards - Applicability VIL
Page 53 and 54: General Info - ANSI/ASME B73 pumps
Page 55 and 56: What type of plant? • Class of Pl

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