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METHODS OF MINE VENTILATION; MINE
FANS, FURNACES, STEAM JETS AND
THEIR RELATIVE ADVANTAGES CON­
SIDERED.*
In A. L. Stevenson's translation of Daniel Murgue's
theory and practice of centrifugal ventilation
machines, we find, as far back as 1657, Agricola
in a very interesting work gives particulars
and drawings of a ventilator for mines driven by
water power. Also at the Hartz mines, nearly
200 years ago. a fan somewhat similar to the
Strove model was in operation. Mr. A. A. Atkinson
gives a brief description of this ponderous
machine in his Key to Mine Ventilation, page 103.
Following this report we find that a commission
appointed by the English House of Commons
to inquire into and investigate the advisability of
the various systems of mine ventilation, then in
vogue, depending upon machinery as the power,
reported as follows: "That any system of ventilation
depending upon complicated machinery is
undesirable, since any disarrangements or fracture
of any of its parts, the ventilation is stopped or
becomes insufficient. That the two systems
which alone can be considered as rival powers
are the furnace and steam jet. Your commission
are unanimously of the opinion that the steam jet
is the most powerful and at the same time least
expensive method for the ventilation of mines."
The fan at this time was in its experimental
stage and was not even considered worthy to be
called a rival to the more powerful steam jet,
either in point of
EFFICIENCY OR ECONOMY,
and must necessarily pass the keen criticism of
both friends and enemies, and pass from one stage
of development to another until it thoroughly
proves its superiority over all other modes of
ventilation.
In 1861 the centrifugal fan was first described
to the North of England Institute of Mining Engineers
by the late Mr. J. J. Atkinson in several
valuable papers on the subject, which clearly defined
its superiority as a mechanical ventilator
over every other system of mine ventilation.
Let us compare the different systems of mine
ventilation, the amount of coal consumed by the
steam jet and furnace as against the fan, per equal
quantities of air produced:
The steam jet would require 1,000 lbs. of coal.
The furnace, would require 350 lbs. of coal.
Open running fan would require 150 lbs. of coal.
Closed running fan, Guibal type, 120 lbs. of coal.
to produce equal qualities, and it is worthy of
note from that time until now the question as
to which fan is superior has been a source of
constant contention, every new inventor claiming
for his invention something much better than his
•By I. Q. Roby, of Uniontown, Pa.
THE COAL TRADE BULLETIN. 47
predecessor. A number of experiments have been
made with a view of determining the truth as to
the advantages one fan possesses over others.
The results of these experiments have varied and
the question to-day still remains unanswered as
to which ventilator is the best, under all conditions.
Now as a mining engineer or a mine manager,
taking all circumstances into account, what
make or style of fan should we adopt at our mine,
and why adopt such make or style of fan? In
bringing the subject up to this point, where we
must decide as to what size and make of fan we
will adopt, three points present themselves for our
consideration:
First, cost; second, durability; third, efficiency.
We will now discuss some of the principles involved
in both fan and furnace ventilation. The
motion of the air current is caused by a difference
of pressure between the two ends of a current,
or, it may be expressed, by a difference of pressure
between the inlet and the outlet. We find
the direction of floor from the higher to the lower
pressure. When the mode of ventilation at a
mine is a furnace the higher pressure is always
the normal atmospheric pressure and the lower
pressure is at the bottom of the furnace shaft.
The same may be said of the steam jet. The fan
at one time operated by any mechanical power
was not supposed to be even a rival.
As practical results have demonstrated the superiority
of the centrifugal fan over all other
forms or modes of ventilators, the steam jet, once
its superior, has fallen entirely into disuse in
Western Pennsylvania, as far as is known by the
writer. And the furnace is following rapidly in
the wake of the steam jet. Its future is foreshadowed
as not being of very long duration. We
no doubt will continue to find a furnace here and
there, especially at operations where there is no
steam used. When we consider the outlay, first
cost and maintenance of the furnace compared
with utility and efficiency, especially in shallow
workings, it is certainly
A VERY EXPENSIVE LUXURY.
The object of the furnace is to produce a motive
column by rarefying the air in the up-cast shaft.
We find the furnace adopted invariably in very
shallow mines where an efficient motive column
cannot be obtained, and where the fan would be
much more desirable and economical. Despite this
fact the furnace is yet in use, therefore, deem it
best to describe its construction.
In building a furnace it is important to so
construct it as to keep the excessive heat of the
fire from the coal on its flanks, and from the rock
above it. Above tne fire should be constructed
a double arch, as the under arch is subject to
constant variations of temperature. Ribs of