The La Jara chronicle., 1907-09-06
The Flow of Water in Pipes.

iTTlSdllOn uepdTtulent Oh tle SOlO-
RADIO agricultural college by the
farmers of the state is: How
much water will a certain sized
pipe carry under a certain head
say ten feet, and what number of
pipe would you recommend to
stand the pressure of say % pounds
per square inch? A short discus
sion of this may be of interest to
many farmers, so let me say that
the quantity of water which given
pipe will carry depends upon
many things: it depends upon the
length of the pipe, the number
and nature of bends in the pipe,
the mum Der and kind of valves in
the pipe, etc. 1t is very difficult
thing, if not an impossible thing,
to derive a formula which will
give results for every case, for the
conditions affecting the flow are
so many and so varied. However
We can approximate and come close
enough for all practical purposes.
The simplest rule L know of is
this: A pipe l foot in diameter
laid on a slope of l to 1000 will
flow approximately l cubic foot
per second. The quantity flowing
varies as the 80 power of the di-
ameter: the quantity also varies
as the square root of the grade or
slope. For an examples: How
much water will "A pipe carry,
which is fifteen inches in diameter
on a grade of s feet to 1000?
Fifteen inches is equal to 15-12 or
81 of foot. If "A pipe l foot in
diameter ON a grade of l foot in
LOCO flows one cubic foot per sec
ond, and the quantity varies as the
% power of the diameter; there
fore the quantity from 10 inch
pipe on a grade of l foot in 1000
would be equal to "a raised to the
50 power. The % power of any
quantity means to take that guam
tity and raise it to the fifth power
then extract the square root.
Hence taking "a and multiplying
it by itself five times (raising it to
the fifth power) will give us frac-
ton whose numerator is 2,125, and
the denominator is 1924. Ex-
tracting the square root of this
fraction we get approximately LIS
second feet. Now, remember the
quantity varies also as the square
root of the slope. In this problem
the slope is not | in 1000, but 3 in
l 900; therefore the quantity will
equal the square root of 3, multi
piled by this LIS, which we OBJ
tanned above, and the result will
be BOB second feet, which is close
enough to answer any ordinary
purpose.
A more exact way of getting at
practically the same problem, is
this: Take 2-1OO, multiply it by
the length of the pipe, divide this
by the diameter in feet, or part of
foot, then add 1.5. Divide the
head under which the water flows,
expressed in feet, by this result;
extract the square root of the quo
tient. Now, take the result you
have, multiply it by the square of
the diameter, expressed in feet, or
parts of foot, and then multiply
the result by 6.3, and you will have
the quantity flowing in cubic feet
per second. Remember the di-
mensions of the pipe must all be
in feet not inches.
For example: Suppose we have
pipe six inches in diameter, 100
feet long, under head of % feet;
find the quantity of water flowing.
Following the above rule, we
would have 100 feet multiplied by
.02 equals 2 feet. Now, 6 inches
equals D of foot and divided
by . equals 4. Adding 1.5 gives
5.5. The head, % feet, divided by