April 24, 2019 522 view(s)
Firemen and Canaries - A History of Gas Detection

Firemen and Canaries - A History of Gas Detection

The wonders of modern technology are an amazing thing. The ability to always be ‘on’, AI that can search the internet for you, and movies with fantastic special effects never fail to amaze. In the world of the gas detector, modern technology can be the difference of life and death, so its history is very important.

It is a high stakes gamble when you don’t know what may be in the air you’re breathing. Everyone knows about the canary in a coal mine, but how did we get from there to here?

The Monk in the Mine

Believe it or not, those noisy little birds were not the first gas detectors in history; people were. During the Industrial Revolution one unlucky miner was chosen to check the mine for gas. The miner would usually be a new hire or in some cases even a child. These brave individuals were called firemen in North America, and monks in Europe.

After the preceding shift had left this young man would be sent into the mine with a damp cloth over his face and a lamp in his hand. He would walk through the mining area looking for pockets of methane.

A small pocket of methane would cause his lamp to erupt in flame. The damp cloth would provide some protection from damage to the youth’s face. A larger pocket would mean serious burn injuries or death. Miners accepted this as the cost of safety for everyone else.

Clearly a better gas detector was needed. This led to the introduction of Safety Lamps.

Eureka! The Safety Lamp

Around the start of the 19th William Reid Clanny, an Irish scientist, invented the world’s first safety lamp. This was a huge leap towards safer gas detection. Though others would create better versions of the safety lamp quite soon after, the safety lamp itself acted as both a gas detector and a guiding light for over a century more.

The idea was to have a flame lit in a semi-sealed container. Air could flow in, but the flame could not get out.

The lantern would have three notches. The flame would normally reach the second notch. If the lamp were to enter an area with methane or a high concentration of oxygen the flame would reach up to the third notch. When the lamp went into an area with low oxygen the flame would go down to the first notch.

The design of this safety lamp has been able to work well enough that two hundred years later, although with very limited use, they are still being manufactured in the UK. Still, the safety lamp was not without its issues. In addition to only working in confined spaces with flammable gases, it also needed constant attention. There would be no alarms that went off when there was gas in the air.

Everybody's Heard of the Canary

In the early years of the 20th century, much later than most people realize, Scottish physiologist John Scott Haldane began telling miners they should use canaries in their coal mines in addition to safety lamps.

Canaries are loud and annoying birds. They like to sing and make noise. They also coincidentally have a breathing system that is very similar to that of humans. Miners would pick a sickly-looking canary (for extra sensitivity to gas) and carry it around in a cage as they mined.

If the bird was chirping away happily they knew everything was fine. When the canary began to shake its cage, the miners knew it was time to pick a new spot. Were the bird to go completely silent it was probably dead and that meant it was time to leave immediately.

Canaries were popular with the miners, who often raised them as pets. These birds would also continue to be used in many places around the world up until 1986, when the British became the last to mandate the use of electric sensors in place of the birds.

Despite its popularity among some miners, canaries were not versatile and were rarely if ever used outside of mines. Scientists were in need of additional methods to detect gas and chemicals in the air.

Entering the Modern Age

In 1925 Japanese scientist Dr. Jiro Tsuji invented a method of detecting gases using light-wave interference. A few years later Tsuji founded Riken Keiki Co., better known as RKI Instruments. Although this would be the first company in history dedicated to modern gas detection methods, it would not be the last.

Tsuji’s method of gas detection has the benefit of acting as an “open path” gas detector, where one positions the light and the receiver farther apart. Despite being the first modern method of gas detection, an updated version of Tsuji's light-wave sensors are still in use today.

A few years later, in 1927, Dr. Oliver Johnson, an American scientist, would make history by inventing the first Thermal Conductivity Detector (TCD) using a platinum catalyst and a Wheatstone circuit bridge. He would go on to found Johnson-Williams.

This type of gas detector is very rugged and can be used in a wide range of situations with the cost that it requires careful calibration before each use.

New Gas Detection Breakthroughs in the '50s

Thirty years after Johnson's creation of the TCD, in Australia and New Zealand (independently and at the same time), the invention of Flame Ionization Detectors once again brought an alteration to the gas detection landscape. These devices, commonly abbreviated as FID, detect the ionization of gases when they have exposure to flame. These detectors are very accurate but require a constant fuel supply for the flame, which can be dangerous in certain environments.

Not long after the invention of the FID, the development of metal-oxide semiconductors led to further advancements in gas detection technology. Basically a computer chip with sensors on it, these devices could detect changes in the electromagnetic field caused by gases.

The metal-oxide semiconductor sensor is very accurate and hardy, being viable in even the most rugged situations, however they are also much more difficult to use than most other methods of gas detection.

The 60s also saw the invention of electrochemical sensors. Coming from Japan, electrochemical sensors work using a simple electrical circuit. They can detect low concentration of gases. Electrochemical sensors, however are not as durable and can be prone to leakage.

Into the '70s

The next major breakthrough, which would appear in the ‘70s, was the Photoionization Detector (or PID). These devices bombard the air passing through with photons, causing the molecules to ionize, creating an electric charge. The change in the charge will depend on the types of molecules passing through the gas detector.

Photoionization detectors are great for searching out low concentrations of gases. The downside is that they are unable to work well at higher concentrations. In Addition, they are not able to indicate what they are detecting.

These technologies continue to see improvements as time goes on. Whereas early devices were clunky and difficult to use, later devices are much sleeker and less intrusive. The efficacy and reliability of these gadgets has also gone up, with each device filling its own niche.

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