TM 5-813-9
1) Type of pipe: New steel
2) Speed of shock wave: (a) 2,690 ft/sec
3) Fluid under control: water static head: (H) 20 ft
4) Length of main to nearest reservoir: 3,400 ft
5) Critical interval:
2L
2 3400
'
' 2.53 seconds
(t) t '
a
2690
6) Flow (gallons/minute) 5000 discharge line size: 10 in.
7) Normal system velocity: (V) 6.48 ft/sec
8) Surge head rise for instantaneous closure: (N = 1)
&a)V(
17431
)H '
' 544.7 236.1 R
'
gN
(32) (1)
9) Total head of surge wave: (surge head plus static head)
)H + H= 20 + 545 = 565 ft = 245 psi
10) Number of critical intervals (t)
11) Seconds required for control cycle: (N x t) 1.6 x 2.5 = 4.1 seconds
12) Recommended control valve size: ** inches
13) Control valve head loss: ** ft
Derived from equations:
Solved simultaneously for instantaneous closure condition: f (t + x)=0
**Consult Manufacturer of Selected Equipment
Figure 4-5. Example Water Hammer Potential Calculation
4-6
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