The gas stove is the simplest stove made. It consists of a burner or burners of different shapes mounted on a suitable frame. The best example of a gas burner is a pipe with holes punched in it, where the gas flows out and is set on fire. This pipe may be coiled into a circle and make a round burner, or the holes may all come at the end, which is arranged to spread the gas into a disc shape.
9. Burners. Stoves are usually made with different sizes of burners. One manufacturer states that the gas stoves made by his firm consume per top burner per hour fourteen to eighteen feet of gas, and the oven burners consume eighteen to twenty feet when the gas is turned on full. Simmerers consume much less than this.
10. Simmerers. Every gas range should have a simmerer on it. This is a small burner, usually about an inch in diameter. After a large kettle full of food has been heated to boiling, this burner may keep it simmering for hours, using very little gas. This burner will keep small kettles of food boiling.
11. Air Mixer. Gas escaping from any pipe will burn, but it will burn with a yellow flame. To make gas burn with a blue flame—that is, to secure complete combustion—air must be mixed with it. This is done in the air mixer (Fig. 4). The blue flame is desirable for cooking because it is hotter than the yellow flame and does not blacken the cooking utensils.
Gas passes thru the air mixer before entering the burner. Sometimes the air inlet is only a hole put in the under side of the pipe. The opening for entrance of air is shielded so that the gas will not escape from the mixer, but will go on into the burner. A gas pipe looks about half an inch in diameter, but the stream of gas which is allowed to flow into the burner is very small, in some cases being about the diameter of a darning needle. The opening for air is so large, that a person's finger may be put into it.
Too much air interferes with the burning of the gas; in fact, there can be so much air mixed with gas that it will not burn. The air mixer regulates the amount of air which flows into the pipe. Once this is adjusted for the kind of gas to be used, it seldom needs to be changed. The air shutter has to be changed, however, if the gas pressure varies markedly from time to time. Readjustment may be required if the stove is moved and connected with a different supply of gas. When adjusting the mixer for high pressure, artificial or natural gas, close the shutter until the flame will not blow away from the cone, but will burn with a blue, almost colorless, flame.
Fig. 4. Part of gas stove
showing air mixers.
12. Regulating the Gas. The amount of gas which passes into the stove is also regulated, first, by adjustment of the size of the small opening thru which the gas must flow. Once this is adjusted, it does not need to be changed so long as the gas comes from the same source. Second, the flow of gas is regulated by the lever valve. As the valve is turned, the flow of gas is restricted so that it flows less swiftly. The size of the stream of gas going into the stove always looks the same regardless of its speed. When the rate is not so fast, the fire burns lower because less gas comes to it during every unit of time.