The second week of training, at college, dealt with ventilation, fires and the gases that are released when coal is worked. Ventilation is achieved within pit working by a huge fan situated at the top of one (upcast) of the two shafts, usually the man riding shaft. The fan sucks air up the shaft from the underground workings. Because of this air displacement, air from the top other shaft (downcast) is drawn down this shaft into the workings. A system of air doors allows the air to circulate around the mine. A good ventilation system is an obvious necessity.
Roadways that connect intake and return roadways need to have a barrier to stop air circulation from taking a shortcut. This barrier must be movable and air doors are used. There are always at least two air doors in tandem; if one door is opened the other remains closed. To have both doors open at once would cause serious circulation problems by allowing air to bypass some of the mine.
When coal is released from a coal face, poisonous, and potentially explosive gases are also released. Providing there is good ventilation these gases are easily dispersed out of the pit.
The ‘Deputy’ or ‘Fireman’ is the charge-hand of the district. He is responsible for all aspects of ‘his’ area, usually a coal face. The Deputy and the ‘Shotfirer’s’, both of whom are explosive trained, are constantly aware of the need to test for the presence of ‘firedamp’ which is a mixture of gases containing mainly Methane. Deputy’s and Shotfirer’s are middle-management.
Methane is easily detected with the aid of a safety lamp which the Deputy and the Shotfirer carry at all times. The modern safety lamp is an updated version of the original lamp that Sir Humphrey Davy designed in 1815. Since its introduction, the Davy lamp has stood the test of time, and has been the means of saving innumerable miners lives. The safety lamp incorporates an oil lighted wick. The flame cannot make direct contact with the outside of the lamp because of small mesh metal gauze. The flame cannot traverse across this gauze, but air can circulate within the lamp.
In normal air the safety lamp flame burns yellowish, but if Methane is present in the air, the flame burns with a slight bluish tinge at the edges of the yellow flame. The amount of gas present determines the shape of the bluish flame. An equilateral triangle of the blue flame indicates approximately to a two to two and a half percent presence of methane. A mixture of between five and fifteen percent gas in air is explosive. Any percentage of gas showing its presence on a safety lamp is regarded as potentially dangerous.
Underground fires, we were informed, are caused in a number of ways. Naked lights, flames from explosives, friction caused by machinery, defective electrical apparatus and spontaneous pressure combustion. All were discussed, and the urgent need to be aware how they can start, and what actions to take to contain them at source.
The rest of this chapter relates to courting his future wife, Brenda, and can be found on Jack Gale’s website