Gas cylinder

“ The air that traverses this conduit is distributed through the annular space between the piston and cylinder. The hot gas derived from combustion can therefore never introduce itself into this annular space, and consequently cannot come into contact with the rubbing surfaces of the cylinder and piston.
As the quantity of air introduced at every stroke is constant, the work developed at every stroke is varied by regulating the temperature of the gas that fills the cylinder. When the temperature falls, the pressure, and consequently the work developed, diminishes. ”

“ Hitherto, there has been much difficulty in controlling the outrush of gas from these cylinders, for the internal pressure often amounts to six hundred pounds on the square inch. By the aid of a new regulator, invented by Messrs Oakley and Beard of London, this difficulty is at once obviated. The regulator consists of a small india-rubber bellows inclosed in a brass box, which screws upon the nozzle of the gas cylinder. By an ingenious device, as the bellows top rises with the pressure of the gas, a screw valve descends upon the opening in the cylinder. ”

“ Scavenging Engines. As the piston does not sweep out all the cylinder volume because of the space left at the end of the cylinder for compression, more or less burned gas remains in the combustion chamber which dilutes the active mixture taken in on the suction stroke. Not only are the residual gases useless in generating heat but they also occupy a considerable space in the cylinder that might otherwise be filled with a heat producing mixture. ”

“ From such a "blank" a cylinder destined to hold 100 feet of compressed gas can be constructed, and the first operation is to heat the "blank" in a furnace, and afterward to stamp it into the cup-like form shown in Fig. 2. To all intents and purposes this represents the end of a finished cylinder, but it is far too bulky to form the end of one of the size indicated; indeed, it in reality contains enough metal to make the entire vessel. By a series of operations it is now heated and drawn out longer and longer, while its thickness diminishes and its diameter grows less. ”

“ In the cylinder only the best grade of GAS ENGINE cylinder oil should be used, which according to different makers has a flash point ranging from 500 to 700 degrees. Using cheap oil in the cylinder is an expensive luxury. In general, the oils having the highest flash points have also the objectionable tendency of causing carbon deposits in the combustion chamber and rings which is productive of preignition and compression leakage. ”

“ To insure a perfect combustion of the mixture of gas and air, I find that the sheet iron cylinder should be about ten inches high and two inches diameter. Over such a cylinder, with the upper end covered with wire gauze, it is an easy matter to fuse carbonate of soda, or other substance requiring a bright red heat. When the combustion is perfect with the above cylinder, the flame is of a pale blueish white color, like that of a solid flame from alcohol but much hotter. ”

“ Presence of Water in the Cylinder.—It may sometimes happen that water may find its way into the cylinder with the gas by reason of the bad arrangement of the piping. It may also happen that water may enter the cylinder through the water-jacket joint. Again, the presence of water in the cylinder may be due to condensation of the steam formed by the chemical union of the hydrogen of the gas and the oxygen of the air, which condensation is caused by the cool walls of the cylinder. ”

“ Another difference between the actual and theoretical results obtained is that due the perfect combustion in the calorimeter and the imperfect combustion in the engine. Since some gases require more air for their combustion than others, less of the first gas will be taken into the cylinder on a charge than the latter, which tends still further to balance the heating effect of rich and lean gases in the cylinder. ”

“ Only one cylinder has been explained here, but most engines have several, each working at a different stage, so that the power is exerted on the shaft continuously. For instance, take a four-cylinder engine; on the instant that the first cylinder is exploding and driving the shaft, the second cylinder is compressing gas for the next explosion, the third is getting a fresh supply of gas, and the fourth is cleaning out the waste gas of the explosion of a second before. ”

“ Tightness of the Cylinder.—The amount of power developed depends principally on the degree of compression to which the explosive mixture is subjected. The economical operation of the engine depends in general upon perfect compression. It is, therefore, necessary to keep those parts in good order upon which the tightness of the cylinder depends. These parts are the piston, the valves, and their joints, and the ignition devices whether they be of the hot-tube or electrical variety. In order to prevent leakage at the piston, the rings should be protected from all wear. ”

“ If there be no drain-cock on the cylinder, the difficulty [137] of starting the engine can be overcome only by ceaseless attempts to set it in motion. The leaky condition of a joint as well as the presence of a particle of gravel in the cylinder-casting, through which the water can pass from the jacket, is attested by the bubbling up of gas in the water-tank at the opening of the supply tube. These bubbles are caused by the passage of the gas through the jacket after the explosion. ”

“ Then the gas is carried through the purifier, in which all other impurities are removed.
When thoroughly purified the gas passes into the gasometer. This usually consists of two round iron cylinders of nearly the same size, one inside of the other. The outside cylinder has no roof; the inside has no floor. The sides of the inner one go down into a trench filled with water. Its top is held up by the gas, which comes into it from the purifier. ”

“ A very similar thing happens at each explosion of an internal combustion engine. Into the cylinder is drawn a charge of gas, containing carbon, oxygen, and hydrogen, and also a proportion of air. This charge is squeezed by the inward movement of the piston; its temperature is raised by the compression, and at the proper moment it is ignited. The oxygen and carbon seize on one another and burn (or combine) , the heat being increased by the combustion of the hydrogen. The air atoms are expanded by the heat, and work is done on the piston. ”

“ The size of the flame cannot be increased without destroying the proportion between it and the gauze cylinder, and the size of the cylinder cannot be increased without making a dangerously large chamber for the accommodation of explosive gas. ”

“ While the calorific values of the different gases given in the accompanying table are approximately correct for gases burning in the open air at atmospheric pressure they develop widely different values in the cylinder of an engine because of the effects of compression and preheating. The table serves, however, as an index to the relative values of the fuels under ordinary conditions without compression. While natural gas has nearly eight times the calorific value of producer gas in the open air, its actual heat value in the cylinder is only about 45 per cent greater. ”

“ That large, horizontal cylinder is always nearly half full of it. The gas, which is very light, you know, rises through the upper pipes leading from the retorts, and bubbles up through the tar in the bottom of the cylinder. ”

“ Compressed gas cylinders are painted a distinctive colour, oxygen for example being black and coal gas or hydrogen red; the screw connections to the pumps, and all nozzle {17}and regulator fittings, are made with a totally different screw and therefore cannot be interchanged; the cylinders themselves are bound by law to be reannealed and retested under hydraulic pressure at regular intervals; the steel itself has to be of a guaranteed quality; and, in fact, every possible risk is guarded against. ”

“ At every revolution a certain volume of gas thus goes through the cylinder, proportional to its known capacity. The wheel on the axis works in other toothed wheels, whence, by means of an index upon a graduated disc or dial, placed at top or in front of the gas-meter, the number of cubic feet of gas, which pass through this apparatus in a given time, is registered. ”

“ The cylinder water jacket should always be filled with hot water before trying to start the engine, and will prevent the gas from condensing on the cold walls of the cylinder. Often good results may be had by wrapping a cloth or towel around the carburetor, that has been dipped in hot water. ”

“ The combustible charge introduced into the cylinder is composed of gas and air in such proportions that rapid combustion instead of an explosion takes place, and, to obtain sufficient pressure from its expansion, it is compressed to one third its original volume before being ignited.
In this country the engine is made for the trade in three sizes, from two to seven horse-power, but those of larger power are built when desired. ”

“ The main crank D connects as usual to the piston rod of the power piston A1, and the pump crank F to the trunk air pump piston B2 which drives the other air pump piston B3 and the gas pump piston C2 by a piston rod passing through all three. The gas mixture is not made until the inlet valves A4A5 are reached, so that no explosive mixture exists until it is formed within the cylinder A. The air is first introduced into the power cylinder to discharge some of the hot gases, and when the gas is also admitted the contents of the cylinder are cooled to some extent. ”

“ In motors where carbon has been burned hard, the cylinder interior should then be swabbed with kerosene before proceeding. Work the swab, saturated with kerosene, around the inside of the cylinder until all the carbon has been moistened with the oil. This same swab may be used to ignite the gas in the cylinder in place of using a match or taper. ”

“ But times have changed, and a cylinder of about the same size, but half the weight, is now made to hold four times the quantity of gas at the enormous initial pressure of 1,800 pounds on every square inch. This means the pressure which an ordinary locomotive boiler has to withstand multiplied by twelve. The change is due to improved methods of manufacture and to the employment of mild steel of special quality in lieu of the wrought iron previously employed. The cylinders are now made without joint or seam, and the process of manufacture is most interesting. ”