Ignition

“ Ignition is accomplished by means of a metal tube heated to incandescence by a Bunsen burner. At the proper moment the ignition or timing valve is opened, and the mixed gas and air under pressure being admitted to the interior of the tube, the inflammable gases come into contact with the incandescent metal surface and ignite; the flame at once spreads back to the cylinder and fires its contents, thus producing the motive explosion. ”

“ If we inquire whether the surface of the sun is in a state of actual combustion, like burning fuel, or merely in a state of intense ignition, like a stone heated to redness in a furnace, we shall find it most reasonable to conclude that it is in a state of ignition. ”

“ In practice perfect ignition is seldom realized. This is due not only to the ignition system itself but to poor mixture proportions, imperfect vaporizing of the fuel, and low compression; all of which tend to a slow burning mixture with the attendant losses. ”

“ No: ignition is quite independent of combustion. Clay, chalk, and indeed all incombustible 120 substances, may be made red hot. When a body burns, the light emitted is the effect of a chemical change which takes place, whilst ignition is the effect of caloric alone, and no other change than that of temperature is produced in the ignited body. ”

“ Faulty ignition may have its origin not only in the method of ignition employed, but also in excessive heating of the internal parts of the engine, caused by continual overloading or by inadequate circulation of water. ”

“ The jump-spark or high-tension system of ignition depends on the production of a current at such a pressure that it can jump from one point to another through high resistance, such as is presented by air at ordinary or low temperature, and especially when compressed, the spark occurring as it passes. ”

“ We are now in a position to form the following picture of the processes which follow upon the ignition of a combustible gas-mixture contained in a long tube. First we have the condition of slow combustion; the heat is conveyed by conduction to the adjacent layers, and there follows a velocity of propagation of a few metres per second. But since the combustion is accompanied by a high increase of pressure, the adjacent, still unburnt layers are simultaneously compressed, whereby the reaction-velocity increases, and the ignition proceeds faster. ”

“ Ignition head, which ignites the fuel as it passes from the nozzle of the barrel. With each pull of the trigger on the front grip, one of five charges of incendiary mix in an ignition cylinder is ignited. This pilot flame ignites the fuel as it is propelled from the gun. ”

“ The distributor and timer, together with the ignition coil, spark plugs, and wiring, constitute the ignition system.
The proper ignition of an internal combustion engine consists of igniting the mixture in each cylinder at such a time that it will be completely burned at the time the piston reaches dead center on the compression stroke. A definite period of time is required from the time the spark occurs at the spark plug until the mixture is completely expanded. ”

“ What is the difference between the ignition and combustion of large and small grained powder?
With the large grained, the ignition is more rapid, but the combustion slower; with small grains, the contrary is the case. ”

“ It is the purpose of the ignition system to raise a small portion of the mixture to the combustion temperature, or the temperature at which the air and fuel will start to enter into chemical combination. When combustion is once started in a compressed combustible gas it will spread throughout the mass no matter how small the original portion inflamed. The rate at which the flame spreads through the combustion chamber depends upon the compression pressure, the richness of the mixture, the nature of the fuel and upon the number of points at which it is ignited. ”

“ Ignition, or the increase of heat in a solid body, is another source of light, and is well illustrated in the production of illuminating power from the combustion of tallow, oil, wax, camphine or coal gas. ”

“ After a few blasts blow into the burning fuel, directing the stream partly towards the dead coal, when it will be found that the ignition will extend much more rapidly than under the common method of blowing furiously into the flame at random. ”

“ Imperfect Ignition.—The difficulties encountered in starting an engine, and caused by imperfect ignition, vary in their nature with the character of the ignition system employed, whether that system, for example, be of the electric, or of the incandescent or hot tube type. Frequently it happens that in starting an engine a hot tube may break. If the tube be of porcelain the accident may usually be traced to improper fitting or to the presence of water in the cylinder. ”

“ The phenomena of electrical ignition, whether taking place in gaseous, fluid, or solid bodies, always seem to be the result of a violent exertion of the electrical attractive and repellent powers, which may be connected with motions of the particles of the substances affected. ”

“ The progress both of ignition and of combustion is accelerated, not uniform. In proportion as the grains are ignited, the gases evolved increase in volume, and as the progress of combustion continues to generate gases, the tension of these increases, until, as we have seen, the pressure rises as high as 42 tons to the square inch. ”

“ For the best results the gas must be completely ignited at the point of maximum compression, and the pressure must be established on the dead center, so that the indicator card will show a straight and vertical combustion line. As all gases require a certain length of time in which to burn, the ignition should have LEAD, that is, should be started before the end of the stroke so that combustion will be complete at dead center. The amount of ignition lead required depends on the fuel and the compression. ”

“ The space between the piston and cylinder head in which the combustion occurs is called the combustion space, and the inlet and exhaust valves open into it, the first being that by which the fresh mixture enters, and the second that by which the products of combustion escape. The device for igniting the mixture projects into the combustion space, and the means of ignition in universal use for automobile engines is an electric spark. ”

“ The oxygen in the solar atmosphere, like the hydrogen, is simply glowing with intensity of heat. No process of combustion is taking place. Ignition, strictly speaking, means the initiation of the process of combustion, and a substance can only be said to be ignited when it has been set burning. ”

“ Ignition shield, a cylindrical, thin-metal tube with a conical front end. The shield guides the flame and protects the firer. Eight holes around the base of the cone provide an air intake for burning the fuel. The base of the shield is threaded, and it screws onto the ignition-head body. ”

“ He may get a kick from the handle which will give his arm a nasty jar, or possibly sprain his wrist. These 'back fires' are the result of what is called 'premature ignition,' and therefore belong strictly speaking to the chapter on 'Ignition.' I may merely remark that they are due to the spark-timing gear being too much advanced, the platinum tubes being too long, the burners being too close in, faulty opening of the induction valves, overheating of the motor, or ignition tubes being too hot ”

“ Testing for Ignition Trouble.—If the engine misses without regard to speed, test each cylinder separately by short circuiting the plug with a screw driver, allowing a spark to jump. If all cylinders produce a good regular spark the trouble is not with the ignition system. ”

“ Each part of the mechanism may be counted on to give trouble, and the possibilities are numerous, but in general it may be said that an interference with the proper operation of the engine may be laid to the failure of the ignition system or gasoline supply, a defect of the combustion space in not retaining the pressure, or the overheating of the engine. ”

“ A. It furnishes the electric spark which explodes the charge in the combustion chamber, thus producing the power which runs the engine. It is important that the charge be correctly ignited at the proper time, in order to obtain satisfactory results in running the car. In the Ford car the ignition system is as simple as it is possible for human invention to make it. ”

“ If the gas be copious, the flame elongates into a sharp spire, as well as the top. It is in general reckoned dangerous when the tip changes from the bluish-gray to a fine blue colour, accompanied with minute luminous points, which pass rapidly upwards through the flame and top. When the symptoms are manifestly dangerous, a sudden movement of the hands or body is liable to produce ignition by agitation of the fire-damp. ”

“ The breaks of contact are produced in the explosion chambers by small rocking arms, called the palettes, of which the inside arms are alternately pressed by springs against the surface of the ignition plugs or 'inflammateurs,' and then removed by the action of the cams, the vertical stalks from which lift and hold lifted the outside arms of the palettes. ”

“ The instrument usually employed for the ignition of powder is called a universal discharger. It is represented in Fig. 34. I and I' are insulating rods of glass or sealing-wax, supporting two metal arms, the ends of which can be brought down upon the little central table. ”

“ Fifthly, to ascertain if any residuum or ash is left after ignition, about half an ounce is burned on a clean glass plate, and fired with a hot iron. The explosion should be sharp, and produce a sudden concussion in the air; and the force and power of this concussion should be judged by that of known good quality. Few sparks should fly off, nor should white beads or globules appear, as it would be a sure indication, as we have before explained, of insufficient incorporation. ”

“ At first, a faint, pleasing odor of burning birch steals upon the air, then a light streak of smoke follows the revolving arm, and then the heat within his hand notifies the native that a proper degree of ignition has been attained ”

“ The Fire of Incandescent Lamps.—An active incandescent lamp may be broken in the midst of cool combustibles, even of gun-cotton, without setting them on fire, so rapid is the destruction of the carbon filaments in the open air. But a long continuance of the lamp in immediate contact with a combustible envelope may determine ignition, the more readily the more slowly heat and air pass through the envelope. Thus gummed cotton or other goods will take fire more rapidly than similar goods ungummed or loose. ”

“ It has been found by experiments that in calculating the initial velocity of a projectile, one third of the whole force was lost with a windage of 1⁄10th inch with a shot of 1·96-in. and 1·86-in. in diameter. The bore of the gun being 2·02-in.
Definition of ignition and combustion.
By ignition we understand the act of setting fire to a single grain, or to a charge of gunpowder, and by combustion we mean the entire consumption of a grain or of a charge. ”

“ Starting is accomplished by spraying cold gasoline into the cylinder through the fuel valve in the same manner that the heavier oil is fed during operation, and the ignition is performed by a high tension coil and batteries. No spark time device is used, so that a continuous shower of sparks is thrown into 189the mixture during the starting period. Within a minute after the engine is started, the ignition switch may be opened, the gasoline cut off, and the heavy oil turned on for continuous running on full load. ”

“ But in ignited substances which are porous, so as to give the fire room to move, if this motion be checked by strong compression, the fire is immediately extinguished. For instance, when tinder, or the burning wick of a candle or lamp, or even live charcoal or coal, is pressed down with an extinguisher, or with the foot, or any similar instrument, the operation of the fire instantly ceases.
33. Approximation to a hot body increases heat in proportion to the degree of approximation. ”

“ The gasoline and alcohol flames have their drawbacks, one of which is the starting of the burner and the waiting for the heat. They are also unhandy in directing the flame on parts of the work. As I desired a burner for quick work and one whose flame I could direct at any angle, for repoussé and chasing on copper and silversmith's work, I made the one shown in the sketch to attach to a hose and connected it with the gas pipe of the illuminating system in the house. ”

“ Sometimes also the tanks of crude oil take fire, and these conflagrations are said to present a splendid spectacle,—the resinous parts of the oil burning with a fierce deep-red flame and sending up volumes of smoke, through which are emitted lightning-like flashes exploding the ignited gas. ”

“ If an explosive mixture of inflammable gas and air be passed through and ignited on the surface of a disk of wire gauze too fine to suffer the flame to traverse it, and then surrounded by a chimney, to prevent air from entering, save through the gauze, the flame vibrates, and, the vibration being communicated to the ascending gases, produces a sound varying in pitch and intensity according to the height and calibre of the chimney. ”

“ Air, when rendered impure by the combustion of a candle, but in which the candle will still burn, will not explode the gas from the mines; and when a lamp or candle is made to burn in a close vessel having apertures only above and below, an explosive mixture of gas admitted merely enlarges the light, and then gradually extinguishes it without explosion. ”

“ But these require further investigation.
25. Some ignited bodies are found to be much hotter than some flames. Ignited iron, for instance, is much hotter and more consuming than flame of spirit of wine.
26. Of substances also which are not ignited but only heated by fire, as boiling water and air confined in furnaces, some are found to exceed in heat many flames and ignited substances.
27. Motion increases heat, as you may see in bellows, and by blowing; insomuch that the harder metals are not dissolved or melted by a dead or quiet fire, till it be made intense by blowing. ”