IMPROVEMENTS IN APPARATUS FOR PREVENTING EXPLOSIONS IN COAL MINES, WHICH IMPROVEMENTS ARE GENERALLY APPLICABLE FOR INDICATING OR CONTROLLING THE DENSITIES OF GASES OR GAS MIXTURES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Arnold Budenberg at the Office of
the Commissioners of Patents on the 5th April 1880. A communication from
abroad by Christian Frederick Budenberg and Bernhard August Schaffer, both
of Buckau-Magdeburg, in the German Empire.
ARNOLD BUDENBERG, of Manchester, in the County of Lancaster. "IMPROVEMENTS
IN APPARATUS FOR PREVENTING EXPLOSIONS IN COAL MINES, WHICH IMPROVEMENTS
ARE GENERALLY APPLICABLE FOR INDICATING OR CONTROLLING THE DENSITIES OF
GASES OR GAS MIXTURES." A communication from abroad by Christian Frederick
Budenberg and Bernhard August Schiffer, both of Buckau-Magdeburg, in the
German Empire.
This Invention has for its object the prevention of explosions in coal mines by
giving an indication or alarm when an undue or excessive proportion of pit gas is
present. It may also be arranged to indicate the presence of carbonic acid gas or
other dangerous gases in wells, man holes of sewers, and other places, and consists
in utilizing the different densities of various gases in the following manner:-A
closed vessel of thin sheet metal or other suitable material and containing any
suitable gas or gas mixture, but preferably atmospheric air, is so suspended or
supported in the gas or gas mixture, the density of which is to be indicated or
controlled, that the motion, deformation, or change of volume of the vessel, caused
by an alteration of the density of the medium by which it is surrounded or to
which it is exposed, acts upon an indicator of any known construction, for instance,
an alarm bell, preferably by opening or closing the current of a galvanic battery.
This may be effected in the following manner-A light cylindrical vessel filled
with air is suspended from one end of a scale beam, and the said vessel is guided
at its lower end, preferably by means of a vertical guide pin, while the other end
of the scale beam carries a weight which is adjustable, and a needle of the scale
beam is allowed to play between two set screws, one of which is fixed insulated,
but connected by a conductor with a binding post (positive) of a conducting wire
leading to a galvanic battery, the current of which passes through the other binding
post (negative) to the stand of the scale beam and to the needle. The instrument
is so adjusted that in the highest position of the air vessel the circuit is open, but
closed as soon as the said air vessel falls, in consequence of an increase of light
gases in the surrounding medium; or it may be adjusted that in the lowest position
of the air vessel the circuit is open, but closed as soon as the said air vessel rises in
consequence of heavier gases in the surrounding medium.

page_text: The electric circuit actuates an alarm bell or causes a small explosion, and is
interrupted as soon as the density of the surrounding medium is restored to its
normal state.
Instead of suspending the air vessel from a scale beam it may be suspended from
a helical or other spring, and guided at the bottom by a pin, which touches an
adjustable contact spring when the air vessel falls; or it may be arranged with heavier
gases that the contact takes place by a rising of the air vessel, the current passing
in this case through the stand, suspension spring, air vessel, and contact spring.
Another modification of the apparatus is obtained by supporting the cylindrical
air vessel by a number of feet, arranged at the lower part of its circumference, and
closing the cylinder at top and bottom by a flexible diaphragm, preferably of
corrugated sheet metal, the top end being protected by a hood open at the upper
part, and attached to the mantle of the cylinder by brackets. The two diaphragms
are connected by a central rod projecting below the lower diaphragm, and ending
opposito a contact spring, so adjusted that no contact takes place when tho
cylinder is placed in atmospheric air, but that the lowering of the said rod, or
rising if so arranged for heavier gases, caused by an alteration of the surrounding
medium, establishes a contact with the spring, and thereby closes the current of a
galvanic battery.
When desired, the motion or deformation of the air vessel may be indicated on a
dial by a pointer, which may be actuated by any known means, as for example, the
current of a galvanic battery.