1124

THE COLLIERY GUARDIAN.

June 15, 1917.

Formation of Acetylene from Loose Carbide. — The
same publication, discussing the risk that might result
from throwing calcium carbide on the floor of the
mine, concludes that the production of acetylene in
this manner would be too slow to form an explosive
mixture with air, because the acetylene first formed
would be continuously carried away by diffusion and
air currents. On the whole,” the authors add, “with
reasonable precaution there need be little danger from
explosion of acetylene in mines.” They, however,
instance an accident which happened in a coal mine,
the details of which were as follow: A miner carrying
calcium carbide in a glass bottle stumbled and fell. The
bottle broke, throwing the carbide into some water on
the floor. Acetylene was immediately generated, and
was ignited by the miner’s cap light, severely burning
him.

Acetylene Generators and Lamps.

Starting from the fact that acetylene is produced
when calcium carbide and water are brought into con-
tact the one with the other, it follows necessarily that
the design of apparatus hangs upon the various ways
in which the desired contact can be brought about.
The apparatus, of no matter what design, is known as
a generator. Generators, from the point of view of
use, can be classed in two categories: (1) fixed gener-
ators, and (2) portable generators; and from the point
of view of their method of production of acetylene,
into three classes: (1) generators with fall of water
on to carbide, (2) generators with fall of carbide into
water, and (3) contact generators (sometimes called
“ dipping ’’generators). Finally, from the working
point of view, they can be divided into automatic and
non-automatic generators, these latter all belonging to
class 1. A portable acetylene lamp is a generator in
miniature combined with means of consuming the gas
as it is produced. Broadly stated, all portable acety-
lene lamps belong to class 1, although there are a few
lamps the mode of operation of which belongs to class 3.
All three classes can be further subdivided, but since
these subdivisions refer mainly to the classification of
generators for other purposes, such as for flare lights,
Avoiding and metal cutting, they are not relevant to
the object of the present paper.

The essential variations in lamp design are: (1) In
the means of closing the lamp to ensure a gastight
joint between the two principal parts; (2) in the means
of regulating the flow of water on to the carbide; and
(3) in the design and position of the burner in the
lamp.

(1)	Closing Systems.—All portable lamps having
generators of class 1 can be grouped under one or other
of the following seven systems, the gastightness of the
joint being in every case obtained by the inter-position
of a rubber ring: —

(a)	By direct screwing together of two reservoirs.

(b)	By central screw from below.

(c)	By central screw from above.

(d)	By bridle and pressure screw.

(e)	By multiple screws or side levers.

(/) By bayonet joint.

(g) By eccentric closing.

(2)	Regulating the Flow of Water in Lamps.—In all
lamps having generators of class 1—that is, with fall
of water to carbide—the water feed can either be: —

(«) Automatic, by means of a valve which is always
either open or closed;

(b)	Semi-automatic, by means of an adjustable valve
operating in conjunction with a controlled water
dropper; or

(c)	Controlled, by the use of a cone-pointed screw,
which permits of the flow of water being regulated
according to requirements.

(u) The use of the first, or non-adjustable, type of
water dropper avoids the necessity for regulation, but
it may lead to useless consumption of carbide. Also,
owing to the water feed being calculated for a given
burner consumption, the same size of burner must
always be used. The use of quite clean water is, more-
over, of greater importance with this type of dropper,
in order to prevent the fine delivery orifice from
becoming choked. It has, nevertheless, been found to
be satisfactory in practice, and is preferred by many
large users.

(b)	In the semi-automatic type, a screwed stalk
coned at the lower end passes through the water vessel,
and closes on a valve seating which is riveted and
soldered to the water vessel bottom. The valve can be
turned off or on by screwing or unscrewing the stalk,
and, to a certain extent, the rate of flow of water can
be increased by opening the valve. The ultimate rate
of feed is, however, determined by the construction
of the water dropper, which in these models is a
separate fitting. The water dropper is a turned cast
brass fitting, which screws into the base of the valve
seating, and is, therefore, detachable for cleaning, or
renewal if necessary.

(c)	The controlled type of water regulation enables
the user to adjust the water feed, and consequently
the carbide consumption and the intensity of illumi-
nation, according to his needs. In practice, when
once the regulator is set, it does not require to be dis-
turbed again unless the operator wishes to vary the
light.

Burners.

In order to effect the complete combustion of acety-
lene, burners are so designed as to take in at the jet
the supply of air without which the gas would only
burn with its normally smoky flame. There are now
great numbers of patterns, but in general all burners
are formed either with minute air passages near the
point of issue of the gas, or the gas orifices themselves
are so disposed as to form an air envelope around the
issuing gas. Owing to the intense illuminating power
of acetylene, only very small jets are required, the gas
consumption ranging from about | cu. ft. (3j litres) in
cap lamps to f or | ft. (10J or 14 litres) in a 10-hour
hand lamp.

The candle power obtainable depends upon the
burner consumption and the quality of the burner (as
to the relation between its nominal and its actual gas
consumption when working on a given lamp), and can
be varied at will, within the gas producing limits of

the lamp, by changing the burner. All burners are
marked with their rated consumption, usually in litres,
and are referred to as 3^-litre, 7-litre, or 14-litre
burners, as the case may be. Perfect combustion of
acetylene requires the use of higher pressures than
with coal gas. The efficiency of a burner depends upon
the relation between the pressure at which the gas
consumption has been determined, and that at which
it is used. The consumption of English-made burners
such as are generally fitted to hand lamps is determined
at a pressure equal to 3 in. (76 mm.) of water.
The consumption of cap lamp burners is determined
at a pressure of 2J in. (63 mm.) of water. The actual
pressure developed in these lamps is, however, practi-
cally always less than that at which the burner con-
sumption is determined, and it is, moreover, a
diminishing quantity during the use of the lamp. Con-
sequently, the. actual gas consumption is always less
than that which would correspond to the burner rating.

The burners most frequently used in hand lamps
have a gas consumption of 10 or 14 litres, and are made
either to screw in or to push in. For use with the
push-in type, an extra fitting known as a “ burner
socket ’ ’ is screwed into the burner bracket, the latter,
of course, being a fixed part of the lamp. An addi-
tional fitting known as a “ burner protecting tube ’ ’
is also required. This fitting is a short piece of brass
tubing perforated with air inlets. It fits on the burner
bracket, surrounds the burner, and prevents it from
being accidentally knocked off. It also probably tends
to improve the combustion of the gas.

As it is often useful to have an open flame that will
not be put out by a strong wind, there has been devised
what is known as a “ hurricane ” burner. This burner
—taking practical advantage of the fact that the tem-
perature of ignition of acetylene is very low, 480 degs.
Cent.—is surrounded by a mass of metal, the heat from
which is sufficient to re-light the lamp when extin-
guished by a strong wind or by shot-firing, etc. For
gas consumptions exceeding 14 litres, double jet
burners, in which two streams of gas impinge at an
angle of 90 degs., are often used. The position of the
burner on a lamp is purely a matter of convenience.

After a lamp has been in use for some time, the
burner may become charred at the tip, or the very
minute gas orifices may become choked with dust that
has been carried through in the gas. Small pocket
devices known as “ burner cleaning brushes” are used
to clean the burners externally, and burner wires,
either mounted singly or in a cluster, are carried for
the purpose of clearing out any obstruction in the
gas passages.

Burning Hours and Candle-Power of Lamps.

The length of time which any lamp will burn is fixed
by the weight of carbide it will contain, and by the
size of the burner used. The statement is sometimes
made that a lamp of smaller capacity than a given
standard will burn for the same number of hours. The
desired result is obtained, at the expense of the light,
by using a smaller burner. Or, on the contrary, a cer-
tain small lamp is claimed to give the same or a better
light than another large one. In this case, a larger
burner is provided: the increased illumination being
obtained for a shorter period. (It has been shown the
improved results may be obtained by the use of speci-
ally prepared carbide.) Taking 4-8 cu. ft. per lb. (0-3
cu. ft. per oz.), or 300 litres per kilog. (0*3 litre per
gramme) as the average yield for ordinary commercial
carbide, the approximate time that any lamp will burn
will be: —

Weight of charge, in ounces (or grammes) X 0-3
Burner rating, in feet (or litres)

For example, a lamp holding a charge of 11 oz., and
provided with a lOJ-litre (0'367 cu. ft.) burner will
11x0'3

burn for —C	= say, nine hours. The actual time

0'o67

that a lamp will burn is not exactly determinable
(except by experiment), owing to the number of vari-
able factors, such as quality of carbide, correctness of
water feed, and difference between the rated and the
actual burner consumption. Usually, a lamp will burn
longer than its calculated time, because the pressure
developed in it is less than that for which the burner
is rated. The acetylene flame gives over 12 times the
light of a flat coal gas flame, and about 1*6 times the
light obtainable from an incandescent mantle when all
are burning at the rate of 1 cu. ft. of gas per hour.
A 14-litre burner (one of the most commonly used sizes)
will give about 16 candle-power, and other sizes pro-
portionately. According to Mr. J. W. Paul,* the
American type of cap lamp burning with a flame 1 to
1| in. long, and fitted with a reflector, gives a head-on
candle-power of 4-2 to 6-2, and at right angles to the
flame of 0*87 to 1-45. Without a reflector, the head-on
candle-power of the lamps averages 1*9 to 2-15, and at
right angles 1-9. Thus, even when the small cap lamp
is used, there is a marked superiority over the J to 1
candle-power of a candle or the 1 to 2 candle-power of
the small torches used, for example, in Scottish mines.
If the 10-hour 14-litre lamp is used instead of a cap
lamp, the increased illumination is far beyond that
which can be obtained in any other way. The con-
stancy of the acetylene flame, as compared with the
fluctuating value of other open flames, is also a point
in its favour.

Qualities Required in Mine Lamps.

Good mine lamps should be of compact shape, easy
to keep clean, and made of material durable in itself
and strong enough to resist blows and the usual acci-
dents to which they are liable without deformation.
They should be simple as to closing mechanism and
mode of operation, as well to facilitate rapid handling
in the lamp room as for the convenience of the users.
They should not be too heavy to be held in the hand
for several hours without fatigue, if necessary, or to
be suspended by the hook from a ledge of rock or mine
timber. They should not go out or cause excessive gas
production if inclined, or even if accidentally knocked

* “ Notes on Miners’ Carbide Lamps.” Miners’ Circular
No. 18, United States Bureau of Mines.

over. They should be so self-regulating that when the
flame has been adjusted no further attention is
required. And, finally, they should be well balanced,
and provided with a handle, or hook, convenient for
the service required. “ Cap ” lamps should fulfil
similar requirements, due allowance being made for the
necessary difference in weight and dimensions.

Charging and Management Instructions.

Cleaning and Charging.—A carbide lamp, like every
other kind, gives the best results when properly cared
for. The handling of these lamps is simplicity itself;
nothing in the way of attention is required except
cleanliness. But it is just in the degree of cleanliness
which satisfies the user that the whole matter rests.
The use of dirty water, or omission to rinse out the
water vessel occasionally, may block the water dropper.
Failure to keep the rubber rings and the rim of the
carbide container clean may cause gas leakage at the
joints. A burner charred at the tip or choked in the
bore will either give a distorted flame or not light
at all.

To Charge a Lamp.—Release the clamp, screw, or
other tightening device, and remove the water vessel.
Fill the water vessel with clean water, and replace the
screw plug. Then unscrew the water dropper slowly,
and observe what position it should be set at to give a
steady feed of about one drop per second. Close the
water dropper screw again, and the upper part of the
lamp is ready for work. Then take the carbide con-
tainer, clean it out, and dry it, and put in the required
charge of carbide, but never more than about half full.
A pound of pure calcic carbide yields 1-15 lb. of slaked
lime, and the volume this will occupy depends entirely
upon the way in which the water is brought into con-
tact with it. The lime will swell up, and may occupy
from two to 25 times the bulk of the original carbide.
In lamps having a central perforated water tube, the
carbide is decomposed from the bottom upwards, and
the lime is consequently compressed to some extent, as
it is made by the weight of the carbide above it. If,
however, more than about half the capacity of the
container is filled with carbide, the resulting lime will
swell up until it blocks the water dropper outlet, and
if the vessel is very thin it may crack and burst it.
If the container is provided with a central perforated
tube for equalising the water feed, this is put in place
before filling, and the loose disc dropped over the
carbide afterwards. The parts are then assembled,
care being taken that the rubber jointing ring is in
its place and not defective or distorted in any way.
If the lamp is of the central screw tightening type,
only sufficient pressure should be applied to make the
joint gastight. (Spare lamps, if they have been used,
should be washed and dried, and preferably also
greased before putting away.)

To Light a Lamp.—Open the water dropper screw,
wait a few moments for the air contained in the vessel
to be driven off, then apply a light. The gas (still
mixed with air) will give a blue flame at first, but
after a minute or two the flame will become intensely
white. The shape of the flame should be quite regular.
If lacking in brilliance, and small, the supply of water
is insufficient. Open the regulator very slightly, and
wait until the flame has a clean outline, when it should
seem to be motionless and uniformly bright. If the
flame, instead of becoming steady, flares up, roaring
or whistling at the same time, this indicates that the
water regulator has been opened too widely, and the
increased flow has produced an excess of gas. In order
to bring the flame to its normal state, it is sufficient
to close the water valve and wait. The flame will
regulate itself. Finally, the water valve is adjusted—
a little more or a little less—until the flame remains
steady without any further attention.

To Extinguish a Lamp. — Merely close the water
dropper screw completely. The lamp will burn itself
out from 10 minutes to half an hour afterwards,
according to size of lamp. If the lamp can be left
where the escape of gas involves no risk, and where
the smell causes no inconvenience, it is better to blow
out the flame than to let it burn itself out. By blow-
ing out the flame the burners are prevented from
choking, kept in better condition, and last longer.

In conclusion, the writer desires to express his
acknowledgments and best thanks to the well-known
French acetylene expert, M. Albert Butin, for the
friendly assistance that he has given in the prepara-
tion of this paper.

War Workers’ Committee and Coal Supplies.—A meet-
ing of the War Workers’ Emergency Committee was held
at the House of Commons last week. Several complaints
were considered of the shortage of coal supplies, and of
high prices charged to domestic consumers. Mr. Robert
Smillie, the chairman, presided. It was stated that, while
there was a shortage of coal, the workmen employed at
many collieries—more particularly those working for the
export trade—were working short time, and the output
was being seriously reduced. The committee decided to
ask the Coal Controller to receive a deputation to consider
proposals for the storage of coal for domestic consumption.

Coal Shortage in Switzerland.—The Central Bureau for
Coal Supplies in Switzerland, according to the Journal de
Geneve, intimates that the coal trade has little hope of an
immediate improvement in the situation, and is obliged
only to authorise sales of coal to industries holding less than
three months’ stock. As regards fuel for domestic pur-
poses, the Federal Political Department is about to publish
new dispositions concerning prices and provision for winter
supplies. Coal merchants will be under the obligation not
to deliver any to persons having more than three months’
supply. The Central Bureau draws attention to the fact
that arrangements relative to the importation of coal for
household purposes are not at all favourable, and that only
very small quantities may be expected from Belgium in the
immediate future, that it behoves dealers, in the general
interest, to prevent any abnormal stocking of coal and to
distribute to the best advantage the quantities at their
disposal. Belgium, latterly, has only supplied pitch blocks,
and supplies now being delivered of anthracite are the
results of orders issued months ago. The opinion is
expressed that the time is not far distant when there will
neither be anthracite nor pitch blocks available.