Acetylene, The Principles Of Its Generation And Use

F >> F. H. Leeds and W. J. Atkinson Butterfield >> Acetylene, The Principles Of Its Generation And Use

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The data (except in the column headed "cost per 100 candle-hours") refer
to the illumination afforded by medium-sized (0.5 to 0.7 cubic foot per
hour) acetylene burners yielding together a light of about 100 candle-
power, and to the approximately equivalent illumination as afforded by
other means of illumination, when the lighting-units or sources of light
are rationally distributed.

Interest and depreciation charges on the outlay on piping or wiring a
house, on brackets, fittings, lamps, candelabra, and storage
accommodation (for carbide and oil) have been taken as equivalent for all
modes of lighting, and omitted in computing the total cost. The cost of
labour for attendance on acetylene plant, oil lamps, and candles is an
uncertain and variable item--approximately equal for all these modes of
lighting, but saved in coal-gas and electric lighting from public supply
mains.

______________________________________________________________________
| | | | | | |
| | |Candle- | Number |Aggregate| Cost |
| | |Power of| of | Candle- | per |
| | Description of | each |Lighting | Power | 100 |
|Illuminant. | Burner or Lamp. |Lighting| Units |Afforded.|Candle-|
| | | Unit. |Required.|(About.) |Hours. |
| | |(About.)| | |Pence. |
|____________|____________________|________|_________|_________|_______|
| | | | | | |
| |Self-luminous; 0.5 | | | | |
| | cubic foot per hour| 18 | 5 | 90 | 1.11 |
| |Self-luminous; 0.7 | | | | |
| Acetylene | cubic foot per hour| 27 | 4 | 108 | 1.02 |
| |Self-luminous; 1.0 | | | | |
| | cubic foot per hour| 45.5 | 3 | 136 | 0.85 |
| |Incandescent; 0.5 | | | | |
| | cubic foot per hour| 50 | 3 | 150 | 0.49 |
|____________|____________________|________|_________|_________|_______|
| | | | | | |
| Petroleum | Large lamp . . . . | 20 | 5 | 100 | 0.84 |
| (paraffin | | | | | |
| oil) | Small lamp . . . . | 5 | 14 | 70 | 1.31 |
|____________|____________________|________|_________|_________|_______|
| | | | | | |
| |Flat flame (bad) 5 | | | | |
| | cubic feet per hour| 8 | 10 | 80 | 3.75 |
| |Flat flame (good) 6 | | | | |
| Coal Gas | cubic feet per hour| 16 | 6 | 96 | 2.25 |
| |Incandescent (No. 1 | | | | |
| | Kern or Bijou In- | 25 | 4 | 100 | 0.38 |
| | verted); 1-1/2 | | | | |
| | cubic feet per hour| | | | |
|____________|____________________|________|_________|_________|_______|
| | | | | | |
| Candles |"Wax" (so-called) . | 1.2 | 30 | 35 | 6.14 |
|____________|____________________|________|_________|_________|_______|
| | | | | | |
| | Small glow . . . . | 7 | 11 | 77 | 2.81 |
| | Large glow . . . . | 13 | 7 | 91 | 2.90 |
| Electricity| | | | | |
| | Tantalum . . . . . | 19 | 5 | 95 | 1.52 |
| | Osram . . . . . . | 14 | 7 | 98 | 1.00 |
|____________|____________________|________|_________|_________|_______|

___________________________________________________________________
| | | | |
| | | | |
| | | | Equivalent |
| | Description of | Assumed Cost | Illumin- |
|Illuminant. | Burner or Lamp. | of Illuminant. | ation. |
| | | | Pence. |
| | | | |
|____________|____________________|____________________|____________|
| | | | |
| |Self-luminous; 0.5 | Calcium carbide | |
| | cubic foot per hour| (yielding 5 | 1.00 |
| |Self-luminous; 0.7 | cubic feet of | |
| Acetylene | cubic foot per hour| acetylene per | 1.10 |
| |Self-luminous; 1.0 | lb.) at 15s. | |
| | cubic foot per hour| per cwt., inclu- | 1.16 |
| |Incandescent; 0.5 | ding delivery | |
| | cubic foot per hour| charges. | 0.74 |
|____________|____________________|____________________|____________|
| | | | |
| Petroleum | Large lamp . . . . | Oil, 9d. per gal- | 0.84 |
| (paraffin | | lon, including | |
| oil) | Small lamp . . . . | delivery charges. | 0.92 |
|____________|____________________|____________________|____________|
| | | | |
| |Flat flame (bad) 5 | | |
| | cubic feet per hour| Public supply | 3.00 |
| |Flat flame (good) 6 | from small | |
| Coal Gas | cubic feet per hour| country works, | 2.16 |
| |Incandescent (No. 1 | at 5s. per 1000 | |
| | Kern or Bijou In- | cubic feet. | 0.38 |
| | verted); 1-1/2 | | |
| | cubic feet per hour| | |
|____________|____________________|____________________|____________|
| | | | |
| Candles |"Wax" (so-called) . | 5d. per lb. | 2.60 |
|____________|____________________|____________________|____________|
| | | | |
| | Small glow . . . . | Public supply | 2.16 |
| | Large glow . . . . | from small | 2.64 |
| Electricity| | town works | |
| | Tantalum . . . . . | at 6d. per | 1.45 |
| | Osram . . . . . . | B.O.T. unit. | 0.98 |
|____________|____________________|____________________|____________|

_______________________________________________________________________
| | | | | | |
| | |Inci- | Exhaus- |Vitiation | Heat |
| | | den- | tion of | of Air. |Produced.|
| | Description of | tal |Air.Cubic|Cubic Feet|Number of|
|Illuminant. | Burner or Lamp. |Expen-|Feet Dep-| of Car- |Units of |
| | | ces. |rived of |bonic Acid| Heat. |
| | | | Oxygen. | Formed. |Calories.|
|____________|____________________|______|_________|__________|_________|
| | | | | | |
| |Self-luminous; 0.5 | | | | |
| | cubic foot per hour| [1] | 29.8 | 5.0 | 900 |
| |Self-luminous; 0.7 | | | | |
| Acetylene | cubic foot per hour| | 33.3 | 5.6 | 1010 |
| |Self-luminous; 1.0 | | | | |
| | cubic foot per hour| | 35.7 | 6.0 | 1000 |
| |Incandescent; 0.5 | | | | |
| | cubic foot per hour| [2] | 17.9 | 3.0 | 545 |
|____________|____________________|______|_________|__________|_________|
| | | | | | |
| Petroleum | Large lamp . . . . | | 140.0 | 19.6 | 3630 |
| (paraffin | | [3] | | | |
| oil) | Small lamp . . . . | | 154.0 | 21.6 | 4000 |
|____________|____________________|______|_________|__________|_________|
| | | | | | |
| |Flat flame (bad) 5 | | | | |
| | cubic feet per hour| Nil | 270.0 | 27.0 | 7750 |
| |Flat flame (good) 6 | | | | |
| Coal Gas | cubic feet per hour| Nil | 195.0 | 19.5 | 5580 |
| |Incandescent (No. 1 | | | | |
| | Kern or Bijou In- | [4] | 27.0 | 2.7 | 775 |
| | verted); 1-1/2 | | | | |
| | cubic feet per hour| | | | |
|____________|____________________|______|_________|__________|_________|
| | | | | | |
| Candles |"Wax" (so-called) . | Nil | 100.5 | 13.7 | 2700 |
|____________|____________________|______|_________|__________|_________|
| | | | | | |
| | Small glow . . . . |2s.6d.| Nil | Nil | 285 |
| | Large glow . . . . |2s.6d.| " | " | 360 |
| Electricity| | [5] | | | |
| | Tantalum . . . . . |7s.6d.| " | " | 172 |
| | Osram . . . . . . | 6s. | " | " | 96 |
|____________|____________________|______|_________|__________|_________|

[Footnote 1: Interest and depreciation charges on generating and
purifying plant = 0.15 penny. Purifying material and burner renewals =
0.05 penny.]

[Footnote 2: Mantle renewals as for coal-gas.]

[Footnote 3: Renewals of wicks and chimneys = 0.02 penny.]

[Footnote 4: Renewals and mantles (and chimneys) at contract rate of 3s.
per burner per annum.]

[Footnote 5: Renewals of lamps and fuses, at price indicated per lamp per
annum.]

The conventional method of making pecuniary comparisons between different
sources of artificial light consists in simply calculating the cost of
developing a certain number of candle-hours of light--_i.e._, a
certain amount of standard candle-power for a given number of hours--on
the assumption that as many separate sources of light are employed as may
be required to bring the combined illuminating power up to the total
amount wanted. In view of the facts as to dissemination and diffusion, or
the difference between sheer illuminating power and useful illuminating
effect, which have just been elaborated, and in view of the different
intensities of the different unit sources of light (which range from the
single candle to a powerful large incandescent gas-burner or a metallic
filament electric lamp), such a method of calculation is wholly illusory.
The plan adopted in the following table may also appear unnecessarily
complicated; but it is not so to the reader if he remembers that the
apparently various amount of illumination is corrected by the different
numbers of illuminating units until the amount of simple candle-power
developed, whatever illuminant be employed, suffices to light a room
having an area of about 300 square feet (_i.e._, a room, 17-1/2 feet
square, or one 20 feet long by 15 feet wide), so that ordinary print may
be read comfortably in any part of the room, and the titles of books,
engravings, &c., in any position on the walls up to a height of 8 feet
from the ground may be distinguished with ease. The difference in cost,
&c., of a greater or less degree of illumination, or of lighting a larger
or smaller room by acetylene or any other of the illuminants named, will
be almost directly proportional to the cost given for the stated
conditions. Nevertheless, it should be recollected that when the
conventional system is retained--useful illuminating effect being
sacrificed to absolute illuminating power--acetylene is made to appear
cheaper in comparison with all weaker unit sources of light, and dearer
in comparison with all stronger unit sources of light than the
accompanying table indicates it to be. In using the comparative figures
given in the table, it should be borne in mind that they refer to more
general and more brilliant illumination of a room than is commonly in
vogue where the lighting is by means of electric light, candles, or oil-
lamps. The standard of illumination adopted for the table is one which is
only gaining general recognition where incandescent gas or acetylene
lighting is available, though in exceptional cases it has doubtless been
attained by means of oil-lamps or flat-flame gas-burners, but very rarely
if ever by means of carbon-filament electric glow-lamps, or candles. It
assumes that the occupants of a room do not wish to be troubled to bring
work or book "to the light," but wish to be able to work or read
wheresoever in the room they will, without consideration of the
whereabouts of the light or lights.

It should, perhaps, be added that so high a price as 5s. per 1000
cubic feet for coal-gas rarely prevails in Great Britain, except in small
outlying towns, whereas the price of 6d. per Board of Trade unit
for electricity is not uncommonly exceeded in the few similar country
places in which there is a public electricity supply.

CHAPTER II

THE PHYSICS AND CHEMISTRY OF THE REACTION BETWEEN CARBIDE AND WATER

THE NATURE OF CALCIUM CARBIDE.--The raw material from which, by
interaction with water, acetylene is obtained, is a solid body called
calcium carbide or carbide of calcium. Inasmuch as this substance can at
present only be made on a commercial scale in the electric furnace--and
so far as may be foreseen will never be made on a large scale except by
means of electricity--inasmuch as an electric furnace can only be worked
remuneratively in large factories supplied with cheap coal or water
power; and inasmuch as there is no possibility of the ordinary consumer
of acetylene ever being able to prepare his own carbide, all descriptions
of this latter substance, all methods of winning it, and all its
properties except those which concern the acetylene-generator builder or
the gas consumer have been omitted from the present book. Hitherto
calcium carbide has found but few applications beyond that of evolving
acetylene on treatment with water or some aqueous liquid, hygroscopic
solid, or salt containing water of crystallisation; but it has
possibilities of further employment, should its price become suitable,
and a few words will be devoted to this branch of the subject in Chapter
XII. Setting these minor uses aside, calcium carbide has no intrinsic
value except as a producer of acetylene, and therefore all its
characteristics which interest the consumer of acetylene are developed
incidentally throughout this volume as the necessity for dealing with
them arises.

It is desirable, however, now to discuss one point connected with solid
carbide about which some misconception prevails. Calcium carbide is a
body which evolves an inflammable, or on occasion an explosive, gas when
treated with water; and therefore its presence in a building has been
said to cause a sensible increase in the fire risk because attempts to
extinguish a fire in the ordinary manner with water may cause evolution
of acetylene which should determine a further production of flame and
heat. In the absence of water, calcium carbide is absolutely inert as
regards fire; and on several occasions drums of it have been recovered
uninjured from the basement of a house which has been totally destroyed
by fire. With the exception of small 1-lb. tins of carbide, used only by
cyclists, &c., the material is always put into drums of stout sheet-iron
with riveted or folded seams. Provided the original lid has not been
removed, the drums are air- and water-tight, so that the fireman's hose
may be directed upon them with impunity. When a drum has once been
opened, and not all of its contents have been put into the generator,
ordinary caution--not merely as regards fire, but as regards the
deterioration of carbide when exposed to the atmosphere--suggests either
that the lid must be made air-tight again (not by soldering it),
[Footnote: Carbide drums are not uncommonly fitted with self-sealing or
lever-top lids, which are readily replaced hermetically tight after
opening and partial removal of the contents of the drum.] or preferably
that the rest of the carbide shall be transferred to some convenient
receptacle which can be perfectly closed. [Footnote: It would be a
refinement of caution, though hardly necessary in practice, to fit such a
receptacle with a safety-valve. If then the vessel were subjected to
sudden or severe heating, the expansion of the air and acetylene in it
could not possibly exert a disruptive effect upon the walls of the
receptacle, which, in the absence of the safety-valve, is imaginable.]
Now, assuming this done, the drums are not dependent upon soft solder to
keep them sound, and so they cannot open with heat. Fire and water,
accordingly, cannot affect them, and only two risks remain: if stored in
the basement of a tall building, falling girders, beams or brickwork may
burst them; or if stored on an upper floor, they may fall into the
basement and be burst with the shock--in either event water then having
free access to the contents. But drums of carbide would never be stored
in such positions: a single one would be kept in the generator-house;
several would be stored in a separate room therein, or in some similar
isolated shed. The generator-house or shed would be of one story only;
the drums could neither fall nor have heavy weights fall on them during a
fire; and therefore there is no reason why, if a fire should occur, the
firemen should not be permitted to use their hose in the ordinary
fashion. Very similar remarks apply to an active acetylene generator.
Well built, such plant will stand much heat and fire without failure; if
it is non-automatic, and of combustible materials contains nothing but
gas in the holder, the worst that could happen in times of fire would be
the unsealing of the bell or its fracture, and this would be followed,
not at all by any explosion, but by a fairly quiet burning of the
escaping gas, which would be over in a very short time, and would not add
to the severity of the conflagration unless the generator-house were so
close to the residence that the large flame of burning gas could ignite
part of the main building. Even if the heat were so great near the holder
that the gas dissociated, it is scarcely conceivable that a dangerous
explosion should arise. But it is well to remember, that if the
generator-house is properly isolated from the residence, if it is
constructed of non-inflammable materials, if the attendant obeys
instructions and refrains from taking a naked light into the
neighbourhood of the plant, and if the plant itself is properly designed
and constructed, a fire at or near an acetylene generator is extremely
unlikely to occur. At the same time, before the erection of plant to
supply any insured premises is undertaken, the policy or the company
should be consulted to ascertain whether the adoption of acetylene
lighting is possibly still regarded by the insurers as adding an extra
risk or even as vitiating the whole insurance.

REGULATIONS FOR THE STORAGE OF CARBIDE: BRITISH.--There are also certain
regulations imposed by many local authorities respecting the storage of
carbide, and usually a licence for storage has to be obtained if more
than 5 lb. is kept at a time. The idea of the rule is perfectly
justifiable, and it is generally enforced in a sensible spirit. As the
rules may vary in different localities, the intending consumer of
acetylene must make the necessary inquiries, for failure to comply with
the regulations may obviously be followed by unpleasantness.

Having regard to the fact that, in virtue of an Order in Council dated
July 7, 1897, carbide may be stored without a licence only in separate
substantial hermetically closed metal vessels containing not more than 1
lb. apiece and in quantities not exceeding 5 lb. in the aggregate, and
having regard also to the fact that regulations are issued by local
authorities, the Fire Offices' Committee of the United Kingdom has not up
to the present deemed it necessary to issue special rules with reference
to the storage of carbide of calcium.

The following is a copy of the rules issued by the National Board of Fire
Underwriters of the UNITED STATES OF AMERICA for the storage of calcium
carbide on insured premises:

RULES FOR THE STORAGE OF CALCIUM CARBIDE.

(_a_) Calcium carbide in quantities not to exceed six hundred (600)
pounds may be stored, when contained in approved metal packages not to
exceed one hundred (100) pounds each, inside insured property, provided
that the place of storage be dry, waterproof and well ventilated, and
also provided that all but one of the packages in any one building shall
be sealed and the seals shall not be broken so long as there is carbide
in excess of one (1) pound in any other unsealed package in the building.

(_b_) Calcium carbide in quantities in excess of six hundred (600)
pounds must be stored above ground in detached buildings, used
exclusively for the storage of calcium carbide, in approved metal
packages, and such buildings shall be constructed to be dry, waterproof
and well ventilated.

(_c_) Packages to be approved must be made of metal of sufficient
strength to insure handling the package without rupture, and be provided
with a screwed top or its equivalent.

They must be constructed so as to be water- and air-tight without the use
of solder, and conspicuously marked "CALCIUM CARBIDE--DANGEROUS IF NOT
KEPT DRY."

The following is a summary of the AUSTRIAN GOVERNMENT rules relating to
the storage and handling of carbide:

(1) It must be sold and stored only in closed water-tight vessels, which,
if the contents exceed 10 kilos., must be marked in plain letters
"CALCIUM CARBIDE--TO BE KEPT CLOSED AND DRY." They must not be of copper
and if soldered must be opened by mechanical means and not by
unsoldering. They must be stored out of the reach of water.

(2) Quantities not exceeding 300 kilos. may be stored in occupied houses,
provided the single drums do not exceed 100 kilos. nominal capacity. The
storage-place must be dry and not underground.

(3) The limits specified in Rule 2 apply also to generator-rooms, with
the proviso also that in general the amount stored shall not exceed five
days' consumption.

(4) Quantities ranging from 300 to 1000 kilos. must be stored in special
well-ventilated uninhabited non-basement rooms in which lights and
smoking are not allowed.

(5) Quantities exceeding 1000 kilos. must be stored in isolated fireproof
magazines with light water-tight roofs. The floors must be at least 8
inches above ground-level.

(6) Carbide in water-tight drums may be stored in the open in a fenced
enclosure at least 30 feet from buildings, adjoining property, or
inflammable materials. The drums must be protected from wet by a light
roof.

(7) The breaking of carbide must be done by men provided with respirators
and goggles, and care taken to avoid the formation of dust.

(8) Local or other authorities will issue from time to time special
regulations in regard to carbide trade premises.

The ITALIAN GOVERNMENT rules relating to the storage and transport of
carbide follow in the main those of the Austrian Government, but for
quantities between 300 and 2000 kilos sanction is required from the local
authorities, and for larger quantities from superior authorities. The
storage of quantities ranging from 300 to 2000 kilos is forbidden in
dwelling-houses and above the latter quantity the storage-place must be
isolated and specially selected. No special permit is required for the
storage of quantities not exceeding 300 kilos. Workmen exposed to carbide
dust arising from the breaking of carbide or otherwise must have their
eyes and respiratory organs suitably protected.

THE PURCHASE OF CARBIDE.--Since calcium carbide is only useful as a means
of preparing acetylene, it should be bought under a guarantee (1) that it
contains less impurities than suffice to render the crude gas dangerous
in respect of spontaneous inflammability, or objectionable in a manner to
be explained later on, when consumed; and (2) that it is capable of
evolving a fixed minimum quantity of acetylene when decomposed by water.
Such determination, however, cannot be carried out by the ordinary
consumer for himself. A generator which is perfectly satisfactory in
general behaviour, and which evolves a sufficient proportion of the
possible total make of gas to be economical, does not of necessity
decompose the carbide quantitatively; nor is it constructed in a fashion
to render an exact measurement of the gas liberated at standard
temperature and pressure easy to obtain. For obvious reasons the careful
consumer of acetylene will keep a record of the carbide decomposed and of
the acetylene generated--the latter perhaps only in terms of burner-
hours, or the like; but in the event of serious dispute as to the gas-
making capacity of his raw material, he must have a proper analysis made
by a qualified chemist.

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