Machinery's Handbook, 31st Edition
PUMPS
2803
1.00 .90 .80 .70 .60 .50 .40 .30 .20 .10 .0
C H
C Q
C
Centistokes
Viscosity: SSU
10
15
2 25 30 40 50 60 70 80 90100
Rate of Flow-gallons per minute (at BEP)
Fig. 8. Centrifugal Pump Viscosity Correction Factors SSU are Saybolt Universal Seconds. ASTM D2161 covers conversion of kinematic vis cosity to SSU at a given temperature. BEP is Best Efficiency Point . System Head or Total Dynamic Head (TDH): This is equal to the difference between total discharge head and total suction head: h t h t d ( ) h t s ( ) – = For centrifugal pumps, a change in impeller diameter or speed results in a change in head according to the affinity laws discussed in Affinity and Similarity on page 2808. Using the following equation, head can be calculated from impeller and fluid speeds for radial and mixed-flow pumps where the incoming fluid velocity is nearly zero.
η i v i v f g = -------
h t
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