feet, then feet
is
the
23. STORAGE
largest allowable loss per 1,000 feet
a. Requirement.
Determine
the
of pipe. From figure 14, a flow of 25
potable water storage requirement for
gpm and a headloss of 28.5 feet per
the QM depot.
1,000 feet require a minimum diameter
of 1.9 inches.
The next larger size
b. Solution.
From paragraph 9,
available is 2-inch pipe. In the same
Storage requirement = 1/2 (Avg Demand
manner,
the
pipe
size
could
be
x design pop + Large users).
determined for the branch B1 if other
pipe sizes were used or considered on
Design population = Actual population
the main AB.
x capacity factor.
Here, actual population = 50 officers
+ 700 EM = 750 total.
From table 1, for 5,000 people
or
less, the capacity factor is 1.30.
28.5, 2-inch diameter pipe required
on branch B1.
Therefore:
(3) Branch B2.
Flow = 75 gpm,
Design population = 750 (1.30) = 975
length = 300 feet, allowable Hf = 20.7
feet.
Storage requirement 1/2 [(975 x 25) +
47,000] = 35,688 gallons.
The water would probably be stored in
two tanks of approximately equal size.
Naturally
an
actual
distribution
From
figure
14,
3-inch
pipe
is
system would be far more complex than
required.
At this point, the final
the one used in this example.
If
sizes for AB, B1, and B2 have been
there were more sections of main
selected. If a choice of two or more
beyond point B, the headloss from A to
sizes existed for main AB at this
B would have to be added to the
point,
it
would
be
resolved
as
headloss from point B to any other
follows: Since AB is considerably
point in the system.
With this
longer than either B1 or B2, the
exception, the same design steps would
smaller of the possible sizes would be
be
applied
that
were
applied
in
used on AB as this would require
designing
this
water
distribution
considerably less pipe by weight.
system.
EXERCISES
First requirement.
Multiple-choice
air from being drawn into the
exercises 1 through 6 are designed to
suction line, at what minimum depth
test your knowledge of common water
in inches should the auction hose
sources.
be located below the water level?
a. 2
c. 4
1. The intake point for a water
b. 3
d. 5
supply system should be as clear
and deep as possible.
To prevent
3-23
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