The Flame Safety Lamp.
The danger from explosions is ever present in coal mines. Ignition of naturally occurring methane gas can be disastrous. This gas is known in the pits as "firedamp", a mixture of methane gas and air.
Methane (CH4) is odourless, tasteless, colourless, and lighter than air which means it is found near the roof of the mine workings. The most dangerous mixture is between 5% and 15% when an explosion is possible.
One of the duties of all officials of a coal mine was to look at the barometer at the beginning of their shift and record the pressure.
When the weather was bad and the barometer dropped, extra care was needed. All coal seams contain methane, but during bad weather methane seeps back into the main body of the mine from old workings or from the waste areas, therefore gas could begin to accumulate where the air flow was weakest.
When miners know where gas is accumulating it is then possible to dilute the gas by the addition of fresh air, thus lowering the concentration of the gas.
Early coal mines were troubled by methane gas; the coal mine management paid someone to disperse the gas by igniting it with a naked flame. As you can imagine this was a very dangerous occupation and these "firemen" literally risked their lives every time they entered a gaseous area of the mine.
Fireman is widely known as an official of the mine in many area's, even today.
As mentioned previously, historically he had one of the most dangerous jobs. He walked down roads or tunnels with a candle and ignited any accumulated gases he encountered. He held a long stick with a candle at the end. Naturally this exploded any methane present. His only protection was to wear clothing such as wool, or leather, well damped, and his head protected by a hood (sometimes he was referred to as the 'penitent', because his dress resembled certain religious orders in the Roman Catholic Church). Very often the fireman was killed during the operation of igniting the gas.
Inventors worked on developing a flame lamp which could be safely taken into a coal mine without igniting the methane gas present.
In 1815 Humphry Davy invented a safety lamp,  George Stephenson, working in a colliery near Newcastle, also produced a safety lamp that year. Both men claimed that they were first to invent the safety lamp.
However Dr. William Reid Clanny was working on a safety lamp in 1811. In 1813, May 20th., Clanny describes his first construction in a paper "On the means of procuring a steady light in coal mines without danger of explosion", for the Royal Philosophical Society. The lamp was called "bellows"-lamp, a tin lantern with glass window, candle and bellow.
These are some of Clanny's lamps.
In 1848 Clanny was given 100 Sovereigns by The Athenaeum/Sunderland, as a public testimony for "the constructor of the very first safety lamp that was ever invented"
Read more about Dr. William Reid Clanny at www.shirebrook.net.
Many variations of flame safety lamps were tried over many years, but their accuracy in determining the amount of methane gas present was questioned when it was discovered that air could be circulating around the lamp ( I think caused by heat from the lamp ) this resulted in a false percentage of methane being estimated.
The safety lamp burns oil. Inside the lamp is a wire gauze cylinder of fine mesh which forms a cage around the flame. Heat from the flame is dissipated and this prevents the flame from propagating outside of the lamp.
How heat transference in a flame safety lamp is achieved.
1). Convection feeds the flame and cools the lamp.
2). The glass allows radiation.
3). The brass oil vessel uses the principle of conduction and radiation.
4). The two gauzes conduct heat and keeps temperatures low.
5). The steel bonnet conducts, radiates and improves ventilation.
6). The outlet holes in the bonnet top allows convection from the flame and carries the heat away.
The quantity of methane gas present in a particular part of the mine was obtained by switching off cap lights ect. so the mine was in darkness except for the light generated by the oil lamp, holding the lamp up to the roof, lowering the wick, and looking at the colour, size and shape of the flame. If firedamp was present a pale blue flame appeared around the central flame, sometimes referred to as the "blue-cap".
The flame safety lamp also detects oxygen deficiency, known by miners as blackdamp, a mixture of air and carbon dioxide (CO2) which could be found near the floor, usually where the ventilation is inadequate.
This was the lamp I used, the Garforth flame safety lamp. It was also called the "silver lamp" by many because of its silver bonnet.
With the Garforth lamp a sample could be taken from a particular area using an aspirator bulb, the sample is then injected straight into the lamp thus giving a more accurate reading.
As a point of interest the Olympic flame is transported from one country to another using the Garforth GR6S Flame Safety Lamp.
The Olympic flame in London on its global journey through 34 cities, visiting five continents. 2004.
The Olympic flame in Ancient Olympia, Greece.
The Olympic flame being transfered from a flame safety lamp to a torch in London.
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