Engineering Bulletin No 1: Boiler and Furnace Testing | Page 3

tested. It is best to have a by-pass from the usual water
supply direct to the feed pump, or to another pump connected to the
boiler, so that in case of any trouble with the testing barrels, the regular
operation of the boiler may be resumed without shutting down.
The next step is to fill barrels 1 and 2 with water until they overflow at
O. This water should be of practically the same average temperature as
that which is to be used during the test. Barrel 3 should be high enough
above the feed pump so that the pump will handle hot water. Put barrel
3 on a scales, before connecting it to the feed pump, and weigh it. Then
let the water from barrel 1 run into barrel 3, and weigh again. The
second weight minus the first weight is the net weight of water run in
from barrel 1 and is the weight of water contained in barrel 1 when
filled to the overflow. The weight of water in barrel 2 when it is filled
to the overflow can be found in like manner. Mark these weights down.
[Illustration: Fig. 2.]
When the net weights are found and barrel 3 is removed from the scales
and connected to the feed pump, the apparatus is ready to begin the test.
Start with the level of the water about 1 foot below the top of the barrel
3, and drive a nail into the barrel to mark this level. When the test is
finished, the level should be brought to the same point, so that the
water that has passed through barrels 1 and 2 will accurately represent
the weight of water fed to the boiler during the test.
When the test is to begin, stop the feed pump and tie a string around the
gage glass on the boiler to mark the height of the water level in the
boiler. Then start the pump connected to barrel 3. Fill barrels 1 and 2
up to the overflow before the test is started. Then open the valve V on

barrel 1 and let the water run into barrel 3 as fast as the feed pump
draws water from barrel 3. When barrel 1 is emptied close its valve V
and open its valve A so as to refill it.
While barrel 1 is filling empty barrel 2 into barrel 3 in the same way,
and continue to fill and empty barrels 1 and 2 alternately. In this way
barrel 3 will be kept supplied with water that has been measured in
barrels 1 and 2, the net weights of which were found before the test
began. Keep a separate tally of the number of times each of the barrels
1 and 2 is emptied into barrel 3. At the end of the test the number of
tallies for each barrel multiplied by the weight of the water that barrel
will hold will be the weight of water measured in that barrel. The sum
of these weights for barrels 1 and 2 will be the weight of water used in
the test.
With a three-barrel arrangement like this, water can be weighed rapidly
enough to supply 300 boiler horsepower.
Before starting a test make sure that there is no chance for water to leak
into or out of the boiler. See that the blow-off is tight, that there is no
drip from gage cocks, and that the feed-line connections are tight, so
that all the water fed to the boiler will represent accurately the amount
evaporated during the test.
If a meter is used instead of the three-barrel method, make absolutely
sure that the meter is correct, as the accuracy of the test depends on the
accuracy with which the water measurements are made. After a meter is
installed, test it to see that it operates correctly under the plant
conditions.
The water level in the boiler should be the same at the end of the test as
at the beginning. As the time for stopping the test draws near, therefore,
try to bring the conditions the same as at the start. Do not, however, run
the feed pump rapidly in the last few minutes for the test in order to
obtain the same water level. If there is a slight difference in level,
calculate the weight of water it represents and make the necessary
correction to the total weight of water fed.

TEMPERATURE OF FEED WATER.
Every plant should have a thermometer on the feed line, so as to find
the temperature of the feed water. Preferably, this thermometer should
be of the recording type. If such a form of thermometer is used during
the test, it is unnecessary to take the feed temperature at stated intervals,
as the record will