e
boiler is doing the work expected of it; that is to say, we must
find out whether we are wasting coal in making steam and how much
this waste may be. Such a test may be made to discover the
efficiency of the boiler, or the quantity of water it is
evaporating, or the cost of evaporating 1,000 pounds of water.

The United States Fuel Administration recommends that every boiler
plant have some means of daily checking the efficiency of the
boiler and furnace. The simplest and best way of finding out how
efficiently the boiler is working is to make an evaporation test,
as described in this bulletin. All the necessary records can be
made automatically with suitable instruments, although in many
small plants the coal must be weighed on ordinary scales. The
efficiency of the furnace can be found by making analyses of the
flue gases. (See Bulletin No. 2 of the United States Fuel
Administration.)

Too many engineers and firemen have the idea that they are not
fitted to make boiler tests. This is altogether wrong. Any man who
can weigh water and coal and read steam gages and thermometers is
able to do the work required in making a boiler test for
evaporation or efficiency. Such a test requires a knowledge of the
following:

1. The total weight of coal used.

2. [1]The total weight of water fed to and evaporated by the
boiler.

3. The average temperature of the feed water.

4. The average steam pressure in the boiler.

If these four items are known, a series of simple calculations will
show how much water is being evaporated per pound of coal, and the
efficiency of the boiler and furnace.

To make a test, the following apparatus and instruments are
necessary:

1. Scales to weigh the coal.

2. Apparatus to weigh or measure the feed water.

3. Thermometers to take feed-water temperature.

4. Gages to indicate steam pressure.

A boiler test to be of value should extend over a period of at
least eight hours. The longer the test the more accurate the
results.

[Footnote 1: For the sake of simplicity, only the essential
elements of boiler and furnace testing are treated in this
bulletin. For rules covering the refinements for an exhaustive
test, the reader is referred to the boiler test code of the
American Society of Mechanical Engineers. Copies of this code can
be obtained from the secretary, 29 West Thirty-ninth Street, New
York City.]

WEIGHING THE COAL.

The weight of coal used during