Clearwater Republican. [volume] (Orofino, Idaho) 1912-1922, 1913-03-13
Report of Water Inspector.

Lewiston, Idaho, March s, 1918.
To the Honorable Mayor & Council Of
the City Of Orofino, Idaho:
Gentlemen: It has been the object
Of your inspector, in making his test on
the recently installed extension of
water mains in your water system, to
discover if any defective joints existed,
1t has further been his object to run
a test in such manner as he would ex-
pect to have had made were he the in
dividual owner of the water system in
spected, and yet one to which he
would be subjected were he the con-
tractor instead of inspector.
With this view in mind he has SUBJ
jected this extension to what is COM
monty known as the "water hammer
test" While this is the most severe
test to which water line can be put it
is the most common cause of trouble
through lack Of experience in opera
ton.
The nature of the water hammer test
is such that if the system withstands it
successfully it is reasonably safe to
presume that the installation is accept
able to the parties awarding the con-
tract.
The question of the so-called "water
hammer" or hydraulic shock" caused
by stopping the flow in water pipe, is
of great practical importance, as the
shock frequently bursts the pipe.
When liquid is flowing through
pipe there is certain amount of energy
in the liquid, and if we stop the flow
this energy must be used up in some
way. Water being incompressible,
and we stop the flow suddenly, the
energy Of the water is used up in doing
work on the pipe by stretching it, in
creasing its diameter, or forcing out its
joints and thus relieving the excessive
pressure.
The shock pressure is transmitted
along the pipe with constant intensity.
The pressure thus produced is proper
tional to the destroyed velocity of flow
and to the speed Of propagation Of the
pressure wave.
By using the formula from "Merri-
man on Hydraulics we find that the
test resulted in an increase, over your
city pressure, Of 4O8 pounds per square
inch Of surface of the pipe line tested.
While the joints were not as smooth
or as well filled with lead as we would
liked to have found them they were as
well made as could be expected with
the tools with which they were made.
The strength Of the joint does not de-
pend so much on the amount of lead
run into it as does it depend on the
manner in which it is hammered into
place. 1t would appear that your con-
tractor had made fairly good joint
else it would not have withstood pres.
sure of 495 pounds per square inch Of
surface.
In making this last statement we are
presuming that your city pressure is
81 pounds, or that you have static
head of about 200 feet.
We very much prefer using rope
for wrapping the pipe for leading pur.
poses instead of using collar because
this method permits Of a. sufficient
quantity of lead to. run outside the
Joint to fill the joint when it shall have
been driven into place by calking and
thus leaving joint well filled with
lead and one that will require great
excessive pressure to displace.
Tools used in calking should not be
less in thickness than one sixteenth o
an inch less than the space between
the pipe and the bell end of the pipe
This will insure uniform joint.
Relative to intake pipe:
Not knowing your requirements will
give carrying capacity of 4, 6 and 8 incl
rough pipe under two foot head:
Four inch pipe under two foot heat
will carry 116 gallons per minute. 81,
inch pipe under two foot head viii
carry 1928 gallons per minute, and al
eight inch pipe under two foot hea'
will carry 684 gallons per minute.
Should the water fall till there is but
2 one foot head the carrying capacitie
2 would be as follows:
Four inch pipe 50 gallons per minute
, six inch pipe 232 gallons per minut
and eight inch pipe 49l gallons pc
minute.
Respectfully submitted,
E. G. WAGNER,
Superintendent Of Department {
Wafor Workc 4. Caworc aYxiSfor