>> Lastly, too rapid heating, or cooling for that matter, not only shortens
the life of the boiler, it significantly increases the chances of a
catastrophic failure of steam lines or the boiler itself. This is a
major safety concern and nothing you want to be anywhere near if it happens.
As Karl says, firing a cold boiler and shutting down a hot one are tasks
best done slowly. <<
-which brings up the fine art of "banking a fire" -
Much like many present-day computer types who, using their system daily, do not
shut it off. The thermal shock of firing up and shutting down small-scale chips
produces far more wear and tear than steady operation for months on end - and
15 cents a day in extra electricity beats the heck out of $1000 for a new
computer every 15 months.
Similarly, (in the regular revenue days) steam locomotives were seldom allowed
to go cold. To "bank" a fire, you would slide the burning embers forward
(usually) - or to wherever they were least exposed to draft from the grates,
and bury them in a thin layer of unburned coal (or wood). This smothered pile
would smolder for 18-20 hours (if required) and keep the boiler and firebox
from going to room temperature. When the next day's work was to begin, the pile
would be raked back over the grates, stirred, and fresh coal added. in less
than a half-hour, you were ready to bein a new shift.
A regularly working locomotive would only have the fire pulled when it was time
for inspection or maintenance, when a man had to enter the fire box.
Marshall Thayer
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