Miner’s lamp

Also in 1815, but before Davy presented his first lamp to the public, George Stephenson (one of the pioneers in the development of the steam locomotive) quite independently was also working on a safe miner s lamp. He discovered during his experiments that flame produced by a particular gas at a given concentration will not pass through a tube smaller than a certain diameter. While most people have heard of Davy s lamp (it seems that Sir Humphrey received all the credit), it was actually Stephenson s discov-... 

Th. Goldschmidt, 52, 3346 (1958) Safety igniter for miner s lamps prepd from Al-bearing Ce alloys GerP 926654 (1955)... 

We shall begin analysis of this question with the most fundamentally simple phenomenon, that of the critical diameter. The same mixture may burn in a wide tube, but not support flame propagation in a narrow tube whose diameter is less than a certain critical diameter. This phenomenon was discovered by Humphrey Davy in 1816 and became the basis for construction of a safe miner s lamp in which a copper mesh with small openings prevents the possibility of flame propagation from the inside of the lamp to the atmosphere of the mine. In this case the mixture in the narrow tube is combustible (an experiment in a wide tube confirms this), and if combustion is nevertheless impossible, then this is so because of the increase in heat loss with the decrease in the diameter of the tube. By heat loss we mean heat carried to the walls of the tube from the reaction zone and the heating zone of the mixture. The heat transferred from the reaction zone into the unbumed mixture cannot be considered a loss (as was done by Holm) since this heat returns to the reaction zone in the form of thermal energy of the heated mixture. 

An old type of miner s lamp bums acetylene, C2H2, which is made as needed by dropping water onto calcium carbide, CaC2. The lamp designer needs to be concerned about how hot the calcium carbide chamber will get because the lamp... 

The miner s lamp discussed in Problem 7.59 is the basis for this problem, (a) How does the heat of combustion of the C2H2 compare to the heat generated in making it from calcium carbide (b) If we add the generating reaction to the combustion reaction, the overall reaction of the lamp becomes... 

A curious experiment has been described by Price 1 in which a flame is obtained very similar to the inner flame of the Smithells separator. The experiment consists m fixing a glass chimney over the base of a Bunsen burner, and a horizontal wire an inch or two above its upper end (fig. 11). If the height of A above the burner and the rate of flow of gas are correctly adjusted, upon applying a light at C the gas bums with a pale blue flame, and bears a resemblance to the gas cap of a miner s lamp. 

At present, measures such as replace the general electrical equipment and damaged cables can be used to solve not use explosion-proof electric equipment and short circuit fault of the electric cable thoroughly. But now there is no way to completely solve the problem of electrical equipment lost its explosion-proof ability, and the most common method used in coalmine is intensive inspection. The types of electrical equipment that lost its explosion-proof ability showed in accident cases have been collected, and got 5 common types of electrical equipments/devices, these 5 types are electrical switches, miner s lamp, exploder, electric coal drill, junction box, and specific distribution is shown in Figure 2. From the figure, we can know electrical switches, miner s lamp and junction box are the 3 main types of equipments/devices that prone to lose its explosion-proof ability, accounted for about 76.93% in total. 

Divided the external-cause ignition sources into electrical fire and operating fire. 3 types of generic acts are included in Electrical fire electrical equipment lost its explosion-proof ability, not use explosion-proof electric equipment, short circuit fault of the electric cable. Electrical switches, miner s lamp and junction box are the 3 main types of equipments/devices that prone to lose its explosion-proof ability, accounted for about 76.93% in total. 

There are 7 kinds of generic acts of operating fire , and the first four kinds are incorrect blasting operate process, hot-line work, disassembling the miner s lamp, deliberately created open flame, and accounted for 89.83% of the accident ignition sources. 

A related smaU deep-discharge lead-acid battery is the one used for miner s lamps and similar equipment. These are 4-V units which are vented and can be watered. They are designed to deliver 1 A for 12 h between charges. 

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