Safety Apparatus to be Employed for Igniting Fuses Especially Adapted for Use in Blasting Operations in Coal Mines for Preventing Explosion of Fire Damp.
Year: 1887

page_text: Date of Application, 9th Aug., 1887.
Specification Accepted, 30th Sept., 1887
Safety Apparatus to be Employed for Igniting Fuses Especially
Adapted for Use in Blasting Operations in Coal Mines for
Preventing Explosion of Fire Damp.
I, CARL ROTH of Charlottenburg near Berlin, Prussia Empire of Germany Doctor
of Philosophy do hereby declare the nature of this Invention and in what manner
the same is to be performed to be particularly described and ascertained in and by
the following statement :-
My Invention relates to improvements in contrivances for lighting fuses (or match
cords) especially adapted for use in Coal mines and has for its object to isolate the
atmosphere of the gallery or place of operation from both the flame of the material
employed to ignite the gun powder of the fuse and the flame arising from said gun
powder when lighted so that any fire damp present is prevented from coming into
contact with the said flames and consequently from being ignited.
In cases where it is impracticable to light the blasting cartridges by aid of electricity
and fuses must be employed for the purpose there has hitherto been great danger of
explosion from the presence of fire damp. On the one hand the atmosphere of the
gallery or place of operation is allowed to come in contact with the flame or igniter
to be applied to the fuse and on the other hand the ignition of the fuse produces a
flame that violently rushes out into and burns for a short time within the atmosphere
of the said gallery or place of operation.
In order to isolate both these flames from any contact with the atmosphere of the
gallery or place of operation is the object of my Invention.
According to my Invention I pass over the end of the fuse to be lighted and secure
thereto a tubular piece so as to cover the end of the fuse and also to provide a space
or chamber in which I place the fuse igniter which may be any fulminating priming
or cap and I detonate the latter inside the said chamber either by mechanical or by
chemical means. The flame thus produced immediately ignites the gun powder of the
fuse and the flame generated by the ignition of this powder rushes back into the said
chamber and is retained within the same and cannot enter the surrounding atmosphere.
The heat of the said flame is taken up by and dispersed through the walls of the said
tubular piece which for this purpose may be made a good conductor of heat. In this

page_text: manner the atmosphere of the gallery or place of operation is isolated from contact
with flame and danger of ignition of fire damp is obviated.
of
My Invention may be carried out by a variety of ways but in order that the nature
my Invention and the manner in which the same is to be performed may be fully
understood I will describe modes of carrying out the same in practice reference being
had to the accompanying drawings.
Figure 1 shows in longitudinal section the tubular safety piece provided with a
detonator and Figure 1 represents the needle to be employed for detonating the
same.
Figure 2 is a modification, the tubular piece being composed of two parts the
upper secured to the end of the fuse and the lower one containing the detonator.
Figure 3 is another modification with the tubular piece made of wire-gauze.
Figure 4 is another modification; the ignition being effected by the friction of a
rough surfaced piece against the inner wall of the tubular safety device having
adhering to it layers of a composition adapted to be ignited by such friction.
Figure 5 shows the end of the fuse provided with a fulminating cap or detonator.
Figure 6 represents a modified arrangement in which the detonator or fulminating
cap is exploded by means of an internal pin.
Figure 7 shews the contrivance in place for firing.
In these figures Z indicates the fuse end to be lighted and R the tubular safety
piece. The safety piece R consists of a hollow tube like body preferably made of thin
sheet metal as in figures 1, 2, 4 and 5 or of wire gauze as in figures 3 and 6 the said
gauze when used having preferably meshes about the same as those of the gauze
used in the Davy lamp. This tube is given a length and a width depending upon
the thickness of the fuse used and the duration of the flame produced by the gun
powder core. A tube having a length of about 8 Centimetres, a width of 6 millimetres
and a thickness of about 1 millimetre for its wall will be sufficient in ordinary cases.
Inside the piece R and say at about a distance of 3 to 4 centimetres from the end
into which the end of the fuse is to be inserted a suitable fulminating priming p is
placed preferably between layers of metallic foil or of waterproof paper. Below this
priming the remaining longer part of the tubular piece R is contracted at one place or
at several places the last section thus produced being provided at its side with holes a
and with a hole o in its end.
In using the safety-contrivance described the end of the fuse is inserted into the
piece R so that the said end rests upon or is sufficiently near to the priming p and
then the piece R is secured to the fuse by pressing it regularly there around by any
suitable means such as by means of nippers.
'
Instead of being formed in one piece only the safety device R may be composed
of more than one piece for example it may be formed of two parts as at b and c
Figure 2. The shorter part c is passed over and secured to the end of the fuse and
the longer lower part is provided with the detonator or priming p. For lighting
the fuse the upper part e with the fuse end therein is rapidly pushed into the lower
part so that the edge of the part c comes forcibly against the detonator or priming P,
and the latter is thereby detonated.
In the device shown by figure 4 the lighting of the fuse is effected by rubbing
against an inflammable composition such as those prepared with phosphorous or other
substances which can be ignited by friction. This composition is preferably applied
in layers P on the inner wall of the tubular piece R.
In the modified arrangement Figure 5 a fulminating cap z is passed on to end of
the fuse.
According to the shape of the safety piece R and the nature of the detonator used
for igniting the fuse such ignition may be effected either mechanically by piercing,
percussion or friction or by aid of chemical reactions. For instance in the arrange
ments of Figures 1, 3 and 6 the fulminating priming p may be prepared with or be a
fulminating cap filled up with a mixture of chlorate of potassium, sulphide of antimony
and sulphur and this fulminating priming or cap may be readily detonated by piercing
or striking it with the needles (shown in figure 1º) pushed for that purpose into the

page_text: tube R through the hole o at the end and in doing so, the gun-powder core of the fuse
is ignited and the flames arising therefrom rushes back into the chamber formed by
the tubular piece R between p and o. and in this chamber the flame is confined and
soon becomes extinguished by communicating its heat to the walls of the said chamber
the contracted parts of which when such are used serving to provide an enlarged
surface of contact to facilitate such communication. The combustion gases which are
no longer inflamed or inflammable escape through the orifices a and o (figure 2) or
through the meshes of the wire-gauze (figure 3).
The igniting of the priming by means of chemical reaction may be effected for
instance when a mixture of chlorate of potassium and sugar is employed as the
fulminating composition and for detonating this the tubular piece R may be turned
up vertically at its lower end and on a drop of concentrated sulphuric acid being
poured thereinto through the hole o by means of a small dropping tube the ignition
takes place..
In the arrangement figure 4 E represents a wire of iron the forked ends of which
are roughened and rub when moved against the fulminating layers P placed on the
inner side of the tube R. In this instance the end of the fuse is evenly cut off and
slightly split up and is situated between the fork of the wire E leaving sufficient room
to enable the wire E to be moved without engaging the fuse.
In the arrangement figure 6 the safety piece R is provided with a pin held in
position by a cross piece in the piece R. In lighting this pin is driven forward by a
rod r so that the said pin strikes or penetrates the detonator or fulminating cap p.
In order to cause the flame retained in the flame chamber of the piece R to be more
quickly extinguished the lower division or bottom part of the said piece R may be filled
with a substance which will generate flame destroying fumes or vapours such as a coarse
grained salt or compound containing a considerable amount of water of crystallization
such for instance as sulphate of magnesium carbonate of sodium and others (as shewn
at U figure 4). The flame acting on such salt or compound will cause the latter to
give off water of crystallization and the steam generated therefrom rapidly extinguishes
the flame. Instead of said salts or compounds iron filings may be used for the purpose.
This addition of salts or compounds or iron filings is of great advantage in all cases
where the fuse produces a very hot flame which otherwise would be of long duration.
Having now particularly described and ascertained the nature of the said Invention
and in what manner the same is to be performed, I declare that what I claim is :-
-
First A safety contrivance for lighting fuses said contrivance consisting of a
device for attachment to the fuse so as to cover the lighting end of the fuse and to
provide a chamber or space for enclosing an igniter or detonator and adapted to retain
and isolate flame substantially as and for the purpose hereinbefore described.
Second-The combination with a device such as is claimed by the preceding
claiming clause of salts or compounds containing water of crystallization or capable of
creating flame destroying fumes or vapours and placed in the flame isolating chamber
substantially as and for the purpose hereinbefore described.
Third: The devices herein before described and illustrated severally in Figure 1,
Figure 2, Figure 3, Figure 4, Figure 5 and Figure 6 of the accompanying drawings
for the purpose described.