MIL-HDBK-1022

Surge Pressure

Nominal Pipe Size

Wave Velocity,

inches (mm)

"a"

ft/s (m/s)

2

(50)

3,771

(1149.4)

3

(75)

3,763

(1147.0)

4

(100)

3,736

(1138.7)

6

(150)

3,692

(1125.3)

8

(200)

3,663

(1116.5)

10

(250)

3,639

(1109.2)

12

(300)

3,599

(1097.0)

(2) If valve closure time (T) is less than Tc, it

is equivalent to instantaneous closure and will result in

maximum surge pressure. The equation used to calculate surge

pressure rise for this situation is:

EQUATION: P1 - P = [(V1 - V0)wa]/(Cg)

(2)

where:

P1 =

maximum pressure (psig or Pa)

P=

pump shutoff pressure (psig or Pa) (equal to

system static pressure)

V1

= initial velocity (fps or m/s)

V0 =

final velocity (fps or m/s)

3

3

w

=

specific weight of the fluid (lbm/ft or kg/m )

2

2

g

=

gravitational constant (32.2 ft/s

or 9.81 m/s )

unit constant (144 in2/ft2, 0.101 (kg/m2)/Pa

C

=

a

=

surge pressure wave velocity (fps or m/s)

(3) For example, a fuel storage facility has a

truck loading rack located 2,000 feet (610 m) away. The load

rack is fed by a 600 gpm (38 L/s) pump located at the storage

facility. The load rack is equipped with a deadman apparatus

which is tied to a hydraulically operated diaphragm control

valve at the rack. The valve has a closure time of 1.0

seconds. The pipe is 6-inch (150 mm) diameter carbon steel,

Schedule 40, with Class 150 flanges. The pump shutoff

pressure is 60 psig (410 kPa). Find the critical time of the

system if the loading rack control valve closes.

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