These plants may serve as a fuel supply for gasoline stove as indicated at R or any other source of domestic heating. The usual gravity supply tank is replaced by the hollow wire through which is the gasoline from the tank in the basement.
Mantle Gas Lamps.
—Mantle lamps that are intended for using city gas are much the same in construction as those using the cold-process gasoline gas; the styles of mechanism differ somewhat with manufacturers but all lamps of this kind possess the essential features that are common to all. Either of these gases may be used with open-flame burners, such as Fig. 193, but since the introduction of mantle lamps, the open-flame burners are rarely used for household illumination.
In the incandescent-mantle lamp, the light is produced by heating to incandescence a filmy mantle of highly refractory material. The higher the temperature to which the mantle of a lamp is raised, the greater is the quantity of light produced. The office of the burner is to produce a uniform heat throughout the mantle with the use of the least amount of gas. As ordinarily furnished from the mains, coal gas or gasoline gas is too rich in carbon to be used in mantle lamps without dilution. When gas is burned in a mantle lamp, it must contain sufficient oxygen—which is supplied by the air—to combine completely with the contained carbon and reduce it to carbon dioxide. If insufficient air is supplied, the lamp will smoke and the mantle will soon be filled with soot.
In the use of the various gases—made from coal, gasoline, kerosene, alcohol, etc.—as a fuel for the production of either heat or light, the form of the burner in which the gas is consumed is the most important factor of the system. Without burners in which to generate a satisfactory supply of heat for the desired purposes, mantle gas lamps would never have come into common use. An understanding of the mechanism of the burners of a system is of first importance because of the possibility of the failure of the entire plant through an improper adjustment of the lamps.
If complete combustion of the gas is attained in the burner, the greatest amount of heat will be evolved and the residue will be an odorless gas, carbon dioxide (CO2). If the gas is not completely burned the odor of the gas is noticeable in the air. Incomplete combustion may be caused by an insufficient air supply, which causes a smoky flame; or if a larger flame is used than the burner is designed to carry, some of the gas will escape unburned. In either case the greatest amount of heat is not developed by the burner.
In most burners, whether for heating or lighting—in which gas, gasoline or alcohol is used as a fuel—the principle of operation is that of the Bunsen tube. One noticeable exception to this rule is the burners used with the central-generating systems where the Bunsen tube is a part of the generator.
The gas generated from any hydrocarbon will burn completely, only after being mixed with air or other incombustible gas, in proportions such as will completely oxidize the carbon contained in the fuel.
In Fig. 190 the familiar laboratory Bunsen burner affords an excellent illustration of the Bunsen principle which forms a part of all burners using gas as a fuel. The gas from the supply pipe issues from a small opening A into a tube B and by the force of its velocity the entering gas carries into the tube above it a quantity of air that may be regulated by the size of the opening. If the gas is burned without being first mixed with air, the flame will be dull and smoky but if air is admitted to mix with the gas, an entirely different flame is produced, the characteristic shape of which is shown in the figure.