Page 33 - Know and Understand Centrifugal Pumps

Know and Understand Centrifugal Pumps

Properties of water I - Atmospheric and barometric pressure
readinqs at different altitudes

Altitude Barometric Atmospheric Boiling
pressure pressure point of
water "F
Feet Meters In. Hg. mm. Hg. Psia Feet water

-1000 -304.8 31 .O 788 15.2 35.2 213.8
-500 -152.4 30.5 775 15.0 34.6 21 2.9
0 0.0 29.9 760 14.7 33.9 21 2.0
+500 +152.4 29.4 747 14.4 33.3 211.1
+IO00 304.8 28.9 734 14.2 32.8 210.2
1500 457.2 28.3 71 9 13.9 32.1 209.3
2000 609.6 27.8 706 13.7 31.5 208.4
2 500 762.0 27.3 694 13.4 31.0 207.4
3000 91 4.4 26.8 68 1 13.2 30.4 206.5
3500 1066.8 26.3 668 12.9 29.8 205.6
4000 1219.2 25.8 655 12.7 29.2 204.7
4500 1371.6 25.4 645 12.4 28.8 203.8
5000 1524.0 24.9 633 12.2 28.2 202.9
5500 1676.4 24.4 620 12.0 27.6 201.9
6000 1828.8 24.0 61 0 11.8 27.2 201 .o
6500 1981.2 23.5 597 11.5 26.7 200.1
7000 2133.6 23.1 587 11.3 26.2 199.2
7500 2286.0 22.7 577 11.1 25.7 198.3
8000 2438.4 22.2 564 10.9 25.2 197.4
8500 2590.8 21.8 554 10.7 24.7 196.5
9000 2743.2 21.4 544 10.5 24.3 195.5
9500 2895.6 21 .o 533 10.3 23.8 194.6
10000 3048.0 20.6 523 10.1 23.4 193.7
15000 4572.0 16.9 429 8.3 19.2 184.0

level in the tank is 10 feet above the pump then the Hs is 10. A
positive elevation adds energy to the fluid and a negative elevation
(suction lift condition) subtracts energy fiom the fluid. To the sum
of the Ha and Hs, we subtract the Hvp.

3. The Hvp, vapor head, is calculated by observing the fluid
temperature, and then consulting the water properties graph in this
chapter. Let's say we're pumping water at 50" F (10" C). The Hvp
is 0.411 feet. If the water is 212" F (100" C) then the Hvp is 35.35
feet. The vapor head is subtracted because it robs energy from the
fluid in the suction pipe. Remember that as the temperature rises,
more energy is being robbed from the fluid. Next, we must subtract
the Hf.

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