and the third column the headloss per
storage to a point on the main where a
1,000 feet of pipe.
Knowing any two
branch is connected, is subtracted
of these, the third can be found by
from the allowable headloss to the
drawing a straight line through the
service connection at the end of the
As an example, assume
This will give the allowable
100gpm is flowing through a 1,000 foot
long pipe of 4-inch diameter.
line passing through 100 gpm on the
headloss and the peak demand (flow) at
left column and 4 inches on the second
the service connection, the diameter
of pipe required can be obtained.
headloss of about 12-1/4 feet per
stated before, the nomograph gives
1,000 feet of pipe is obtained.
headloss per 1,000 feet of pipe, so
conversions between the actual length
obtained by calculation.
of pipe and these values must be made.
If the pipe size obtained is one which
c. Headloss by use of figure 15.
is not available, use the next larger
Figure 15 gives the headloss per 1,000
feet of pipe for any C from 70 to 160.
entering the nomograph with the flow
The left column is the coefficient of
rate and the selected pipe size, find
the actual headloss per 1,000 feet.
headloss per 1,000 feet of pipe, the
Convert this loss to the loss for the
third column is a pivot line, the
length of the branch. The headloss in
fourth column gives the pipe diameter,
the branch, plus the headloss in mains
and the right column gives the flow
to the point where the branch connects
The chart is used by drawing
to the main, will give the cumulative
two straight lines intersecting at the
headloss from storage to the service
This cumulative headloss
intersects the two columns to the left
of the pivot line, while the other
intersects the two columns to the
18. SYSTEM DESIGN PROBLEM
right. The same example will be used.
100 gpm flows in a 1,000 foot long
To illustrate the application of the
design steps explained above, a sample
values of the two right columns are
water distribution system will be
known, so a straight line is drawn
designed for the following situation:
through 100 gpm and 4-inch diameter
A QM depot in a theater of operations
This line is extended to
must have a water distribution system.
intersect the pivot line.
line must pass through this point, so
the second line is drawn through the
intersection point on the pivot line
a. A troop strength of 50 officers
and through C = 100 on the left
and 700 EM.
The headloss per 1,000 feet
intersection of the second line with
the headloss column.
A value of 12-
1/4 is obtained. This is shown by the
solid line on the figure.
example of the use of this nomograph
is given with the figure.
d. Sketch of system layout is shown
headloss in the mains can be found by
in figure 16.
use of any one of the above methods.
After having determined the actual
Numbers underlined are lengths of lines,
headlosses in the various sections of
numbers in parentheses ( ) are service
the mains, the actual headloss, from