Modern Mining Lights: From Birds to Flames to LEDs|
Article- October 2011 By Larson Electronics.com
Larson Electronics tripod mounted explosion proof LED light
In today’s modern industries, explosion proof and hazardous location lighting is an integral and critical part of operations that ensures safety and productivity when working with flammable or explosive materials and compounds. Protection against fires and explosions has become a mandatory part of any operations within hazardous locations, and a huge variety of available methods and equipment make providing this protection effective and nearly foolproof. However, this was not always the case.
Some of the most hazardous work areas on earth are in truth not on the earth, but in it. Mining is one of the most dangerous and oldest industrial operations, and it is in the mines that we find some of the first successful instances of explosion proof lighting. Mining companies learned long ago the hazards that come from atmospheres saturated with flammable or explosive materials and compounds, and miners were always aware they were working in an environment that had the potential to end their lives in an instant. Although collapses and cave-ins as well as the respiratory ailments associated with mining were a well known constant threat, fire and explosions were perhaps the most feared. It was one thing to be crushed to death, another to slowly burn.
One of the most well known early methods used by miners to detect the presence of hazardous gases such as methane and carbon monoxide were canaries kept in cages. With super fast heart rates and metabolisms, canaries were very sensitive to increased concentrations of dangerous gases or reduced oxygen levels. The idea, and a workable one at that, was that the canary would become unconscious far before the dangerous atmosphere became too toxic for humans, or worse, reached an explosive potential, thus giving miners a chance to escape before tragedy could strike. Of course, this meant miners needed to keep a watchful eye on a small bird in the midst of their operations, but it’s understandable if this was considered a worthwhile aggravation.
The problem with canaries, however, is that they aren’t much good for providing light. Since mines are by definition underground, and electric lighting did not appear until the late 1800’s, there weren’t a lot of lighting options available. Miners still had to rely on open flames and combustion based lighting to illuminate the dark mines, and it wasn’t an uncommon occurrence for this type of lighting to ignite the mine atmosphere. In fact, the vast majority of explosions and fires in early mines were the result of mine lighting igniting air that had become saturated with coal dust and flammable gases.
It wasn’t until around 1815 that Humphry Davy improved the miner’s chances with the introduction of his Davy Lamp. Extremely crude by today’s standards and certainly still dangerous, the Davy Lamp nonetheless started mining on the road towards lighting that promised to greatly reduce the threat of fires and explosions. Basically an oil lamp with a special gauze barrier separating the flame from the outside atmosphere, a Davy lamp simply cooled any escaping flame before it could escape the lamp and ignite a flammable atmosphere. Although it reduced the incidences of fires and explosions, it was far from foolproof.
It wouldn’t be until 1902 that practical electrical lamps were introduced in mines and removed the need for open flames. Electrical lamps greatly reduced the possibility of fires and explosions, but again, by today’s standards they were hardly safe. Early electric lamps got hot, the batteries were unwieldy and leaked acids, and shattered bulbs and shorted wires were all too capable of causing an accident. By the 1930’s electric lighting was the only mine lighting in use, although the older Davy lamp variations continued to see some use as gas detectors because changes in their flame would indicated the presence of flammable compounds in the air.
In modern times, mine lighting now bears no resemblance to the old safety lighting of the 1800’s. Technology and manufacturing has progressed to a point where some types of hazardous location lighting (Intrinsically Safe) can now be considered so safe as to be incapable of creating any ignition whatsoever. Most hazardous location lighting (Explosion Proof), however, still holds the potential to act as an ignition source due to the electrical current used to heat a filament or gas and create light.
Protection is usually provided by encasing the wiring and lamp assemblies within specially designed housings that prevent ignited gases from exiting the lamp at temperatures high enough to cause ignition. In effect, the lamp is not explosion proof because it “cannot explode”, but rather because it can control any ignition it may cause. If flammable gases enter the lamp and are ignited within the lamp, the specially designed housing slows the gases down so much that they are essentially too cold to ignite the atmosphere outside of the lamp once they escape.
But, as we can see from the progression from oil lamp, to Davy lamp, to electric lamp, technology continues to develop and improve the available mining light options. Nowhere is this more evident than with Light Emitting Diodes, or, LEDs. New lighting technology like LEDs is on the cutting edge of mine lighting development and offers a degree of reliable operation and safety that was unheard of even 50 years ago. Lights like the Larson Electronics EPL-BS-161M-TP1-100 tripod mounted explosion proof LED light produce more light than incandescent lamps, but use far less power and do not burn a filament or gases, and thus produce far less heat.
Since LEDs do not “burn” a filament to create light, there is no hot bulb or burning filament to ignite an explosive or flammable atmosphere. Even better, LEDs won’t break when dropped, can be easily sealed within non-flammable materials, and are durable enough to withstand the abusive conditions often encountered in mining operations.
With the introduction of the LED into the mining industry has come an increased level of safety that no other form of lighting can match. Regardless of their efficiency or long life, the LEDs' ability to produce light with very little heat coupled with its almost unbreakable design gives it an advantage over all other types of hazardous location illumination.
What form mining lights will take in the distant future is anyone’s guess right now, but for the foreseeable future, count on LEDs being at the forefront.