The electric system has especial conveniences for mine pumping because
of its adaptability to long transmissions of power; electric power can
be transmitted to almost any distance, and the pumps can be supplied
with either direct or alternating current motors. A mining outfit can
be easily divided into a number of parts, to facilitate lowering into a
mine, after which the assembling of the parts is a simple operation.
Stationary pumps for mine use are made in two classes: first, vertical
pumps having cylinders in a vertical position in which the over all
height is comparatively great and the horizontal dimensions as small
as possible; second, horizontal pumps with cylinders in a horizontal
position and having for cross dimensions the over all length. The class
of pump to be selected, of course, depends upon the limitations of
the location. In either case, the motor used for driving the pump is
mounted on an extension of the pump base, making a self-contained and
compact outfit.
Engraving, Fig. 243, represents a Quintuplex pump used principally in
mining operations, or wherever large quantities of water are to be
delivered under high pressure in the shortest possible space of time.
The pump here shown was designed to deliver 225 gallons of water per
minute under a head of 1,200 feet. It has five plungers 4 inches in
diameter each and having a uniform stroke of 12 inches.
These pumps driven by electric motors it is said represent the most
economical method of transmitting power, as compared with the best
designs of steam pumps. An efficiency of 80 per cent. is claimed for
these pumps.
NOTE.—It is interesting to know that in one of the largest electric
pumping installations which has ever been made for mining work, the
power is carried 2,500 feet underground at a potential of 3,500
volts and then transformed into 220 volts at the motors. No trouble
has thus far resulted from the high voltage or any other cause; in
regard to danger from underground electric pumps, it can be stated
that accidents due to the use of electricity in such installations
are almost unknown. _Induction motors are arranged to operate without
moving contacts._ They are therefore free from sparks and can be used
in mines where the presence of gases compels the use of safety lamps.
Fig. 244 exhibits an electric induction motor operating a 5-1/2 × 8
portable track pump.
Portability is an important feature in all pumps for mine use; and,
as track pumps may be put into service immediately at any point on a
system of tracks, they meet this requirement better than pumps of any
other form.
Such an outfit can be hauled to any point in the mine and there
operated from some convenient circuit such, for instance, as the
circuit supplying power to mine locomotives.
[Illustration: FIG. 244.]
The pump and motor shown in Fig. 244 are mounted on an iron truck, no
wood whatever being used in construction, so that adjustment cannot be
affected by moisture and an easy running and durable pump is assured.
The pumps are made as compact and strong as possible for mine service,
which is usually exceptionally rough and continuous. They are of the
horizontal type which is best adapted for low passageways and are
designed so as to afford easy access to all parts. The pumps are single
acting and the plungers are provided with outside stuffing-boxes, which
can be packed, and being in sight, any leakage can be quickly detected.
Access to all valves is made easy by the removal of one large hand-hole
cover on the valve chest.
THE STEAM
PUMP
[Illustration: FIG. 245.