ours of continuous running, or such time as may be
required to burn a total of 250 pounds of coal per square foot of grate.

In the case of a boiler using a mechanical stoker, the duration, where
practicable, should be at least 24 hours. If the stoker is of a type
that permits the quantity and condition of the fuel bed at beginning and
end of the test to be accurately estimated, the duration may be reduced
to 10 hours, or such time as may be required to burn the above noted
total of 250 pounds per square foot.

In commercial tests where the service requires continuous
operation night and day, with frequent shifts of firemen, the
duration of the test, whether the boilers are hand fired or
stoker fired, should be at least 24 hours. Likewise in
commercial tests, either of a single boiler or of a plant of
several boilers, which operate regularly a certain number of
hours and during the balance of the day the fires are banked,
the duration should not be less than 24 hours.

The duration of tests to determine the maximum evaporative
capacity of a boiler, without determining the efficiency, should
not be less than 3 hours.

7. STARTING AND STOPPING

The conditions regarding the temperature of the furnace and boiler, the
quantity and quality of the live coal and ash on the grates, the water
level, and the steam pressure, should be as nearly as possible the same
at the end as at the beginning of the test.

To secure the desired equality of conditions with hand-fired boilers,
the following method should be employed:

The furnace being well heated by a preliminary run, burn the
fire low, and thoroughly clean it, leaving enough live coal
spread evenly over the grate (say 2 to 4 inches),[64] to serve
as a foundation for the new fire. Note quickly the thickness of
the coal bed as nearly as it can be estimated or measured; also
the water level,[65] the steam pressure, and the time, and
record the latter as the starting time. Fresh coal should then
be fired from that weighed for the test, the ashpit throughly
cleaned, and the regular work of the test proceeded with. Before
the end of the test the fire should again be burned low and
cleaned in such a manner as to leave the same amount of live
coal on the grate as at the start. When this condition is
reached, observe quickly the water level,[65] the steam
pressure, and the t