Improvements in Safety Lamps.
Year: 1888

page_text: Date of Application, 15th Aug., 1888
Complete Specification Left, 15th May, 1889-Accepted, 29th June, 1889
PROVISIONAL SPECIFICATION.
Improvements in Safety Lamps.
I, VICTOR FUMAT, of Grand ('ombe, in the Republic of France, Engineer, do
hereby declare the nature of this invention to be as follows:-
My invention relates to safety lamps used in Collieries or other places where
explosive gas is present.
It has for its object a novel method of construction of parts of the lamp by which
air is admitted and the products of combustion escape, so that the lamp burns evenly
and regularly and is not affected by sudden gusts of air.
I take a safety lamp of ordinary construction, having an oil vessel at its base,
with a wick, wick tube, and extinguishing apparatus, a transparent cylinder opposite
to the flame and a wire gauze cylinder surrounded by a metal chimney having a wire-
gauze top. Round the upper part of the lamp above the transparent cylinder I
arrange an outer casing of sheet metal to the top of which a suspending ring is fixed,
and at the side of this casing below the top of the metal chimney I make a sufficient
number of holes for the escape of the smoke and products of combustion, and at the
side of the casing opposite the lower end of the metal chinney I make a sufficient
number of similar holes for the admission of air, these holes being covered by a
descending screen fixed to the casing above but open below so that the inlet holes are
protected from any sudden direct gusts of air. The part of the lamp below the
metal casing is provided with a hollow sheath round about one third of its
circumference, serving as a reflector, and having openings through it for the passage
of air.
By the improved method of construction described a column of air is created in the
external metal casing, by means of the upper and lower sets of holes in the latter, and
the passages through the reflecting sheath.
By the operation of such column of air in combination with the inner column
of heated products of combustion, the combustion at the flame is regulated and
equalized.
Thus, if the lamp is oscillated centrifugal action is set up in the two columns,
but the heavier one overcomes the lighter and the regular draught is not affected.
Sudden gusts of air acting upon the outer column may increase the pressure
of the latter upon the inner column of heated gases, but as such pressure acts
simultaneously upon each end of the latter the regularity of the combustion is not
affected.
The draught is caused by the difference in weight between the columns of cold
and heated air, and if the lamp becomes hot the outer air column also becomes heated
by contact with it, decreases in weight and the draught becomes less active; moreover
air which passes through the wire gauze to the flame if heated provides less oxygen
and combustion is lessened accordingly.
In my improved lamp there is therefore a maximum temperature which cannot be
exceeded however long the lamp remains in a dangerous atmosphere, either still or in
movement, and safety is thereby ensured.
Dated this 15th day of August 1888.
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applic

page_text: COMPLETE SPECIFICATION.
Improvements in Safety Lamps.
I, VICTOR FUMAT, of Grand Combe, in the Republic of France, Engineer, 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 and accompanying drawing, that is to say :-
My invention relates to safety lamps used in Collieries or other places where
explosive gas is present.
It has for its object a novel method of construction of parts of the lamp by which
air is admitted and the products of combustion escape, so that the lamp burns evenly
and regularly and is not affected by sudden gusts of air.
I take a safety lamp of ordinary construction, having an oil vessel at its base, with
a wick, wick tube, and extinguishing apparatus, a transparent cylinder opposite to
the flame and a wire gauze cylinder surrounded by a metal chimney having a wire-
gauze top. Round the upper part of the lamp above the transparent cylinder I
arrange an outer casing of sheet metal to the top of which a suspending ring is
fixed, and at the side of this casing below the top of the petal.chimney I make a
sufficient number of holes for the escape of the smoke and products of combustion,
and at the side of the casing opposite the lower end of the metal chimney I make a
sufficient number of similar holes for the admission of air, these holes being if desired
covered by a descending screen fixed to the casing above but open below so that the
inlet holes are protected from any sudden direct gusts of air. The part of the lamp
below the metal casing is provided with a hollow sheath round about one third
of its circumference, serving as a reflector, and having openings through it for the
passage of air..
The accompanying drawing is in illustration of my invention. Figure 1 is a vertical
section through a lamp, figure 2 is a side view of the same, and figure 3 a horizontal
section. c is the oil reservoir, a b a wire gauze cylinder for the admission of air,
g the hollow sheath serving as a reflector, and admitting air for combustion, d a glass
cylinder, e the inner chimney of coarse wire gauze covered by the cap h; k is an
outer sheet metal cone enclosing the cylinder e and covered by the fine wire gauze
cap f, the whole being surrounded by the external chimney or casing i of metal
perforated on the side opposite to the hollow reflector, with holes o, o, about five
millimetres in diameter provided with tubes projecting inwardly for about five
millimêtres. The air required for combustion enters by the holes o at the lower
part of the casing i and passes through the opening into the passage formed by the
hollow reflector which extends round a part only of the circumference of the lamp,
and reaches the circular air distributing chamber from whence it passes through the
gauze a b to the flame.
The gauze a, b, is double, that is to say it is composed of an exterior cylinder of
fine wire gauze and an inner one of coarse wire gauze, so as to distribute the air in
the interior of the lamp. The lamp has an outer metal ring m the same depth as the
wire gauze ab which protects the flame from draughts or gusts of air.
Air drawn in through the holes o, descends by the hollow reflector g figure 3, into the
circular channel, and through the double wire gauze to the flame, the products
of combustion passing up the chimney into the casing i and out through the upper
holes o.
In order to make the combustion as perfect as possible, the lower end of the
chimney is brought down nearly to the top of the flame.
By the improved method of construction described a column of air is created in the
external metal casing, by means of the upper and lower sets of holes in the latter,
and the passage through the reflecting sheath.
By the operation of such column of air in combination with the inner column
of heated products of combustion, the combustion at the flame is regulated and
equalized.

page_text: Thus, if the lamp is oscillated centrifugal action is set up in the two columns, but the
heavier one overcomes the lighter and the regular draught is not affected.
Sudden gusts of air acting upon the outer column may increase the pressure
of the latter upon the inner column of heated gases, but as such pressure acts
simultaneously upon each end of the latter the regularity of the combustion is not
affected.
The draught is caused by the difference in weight between the columns of cold and
heated air, and if the lamp becomes hot the outer air column also becomes heated by
contact with it, decreases in weight and the draught becomes less active; moreover
the air which passes through the wire gauze to the flame if heated provides less oxygen
and combustion is lessened accordingly.
In my improved lamp there is therefore a maximum temperature which cannot be
exceeded however long the lamp remains in a dangerous atmosphere, either still or in
movement, and safety is thereby ensured.
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is:
The combination, in safety lamps, of the transparent cylinder d, perforated
chimney e, and external chimney k with perforated top, external casing i having
inlet and outlet openings o, opening ; communicating with hollow sheath or reflector g,
and wire gauze cylinder a b, arranged and operating substantially as described and
shewn in the drawing.
151 1
1000
EDWARDS & Co.,
35, Southampton Buildings, London, W.C., Agents for the Inventor.