Canaries to catalytic sensors – a short history of gas detection

Toxic gases – an expanding problem

As you’d probably guessed already, the general consensus is the public at large only got their first real introduction to the dangers of toxic gases when they started becoming a serious problem for those working on coal mines. Not just the miners themselves, either, but also those working in close proximity to them, such as tunnellers.

Those in the mines often found themselves having to contend with the risk of explosive gases, as well as the more subtle but equally devastating dangers of naturally occurring toxic gases like methane. Historically, these naturally occurring hydrocarbon gases were referred to as firedamp, derived from the German word for vapour (dampf).

Methane was obviously the most prominent of these, produced as it so often was by the formation of coal, before it was frequently released by unwitting miners. With the expansion of the UK’s coal industry and construction of newer, deeper mines in the latter half of the 17th century, miners had to deal with more instances of firedamp than ever before.

Early gas detection – naked flames and Davy lamps

As you probably know already, the risks weren’t helped a great deal by the fact that workers frequently used candles to illuminate their environment. By the time the dangers of open flames were fully realised, some miners had actually already learned how to identify the presence of unsafe gases in the area by looking for any changes in the shape or colour of their flames. For example, if the tip of the flame turned from yellow to greenish-blue, that was a sure sign that the area was becoming dangerous.

You don’t have to be an expert to see the limits of this method though, and the recognition of those dangers led Sir Humphry Davies to create the Davy flame safety lamp in 1815. Essentially, it was an oil lamp that was designed to be safely used in methane-rich environments. Its flame was contained within a wire gauze, preventing methane from reaching it in high enough quantities to combust. Like humans, fire needs a fair amount of oxygen to survive, so the miners would light it in a safe area, and then if the flame started to flicker or die as they progressed further underground, they’d be able to judge oxygen levels with a reasonable degree of accuracy. And although early Davy flame safety lamps certainly had their flaws, the basic idea was sound. So much so, in fact, that variants of it are still used in some areas of the world today.

The Industrial Revolution and its captive canaries

As well as methane, carbon monoxide was another gas known to pose a deadly risk to miners – and as the world moved further into the Industrial Revolution, the dangers only grew more pronounced. In 1896, there was an explosion at Tylorstown Colliery in Wales. Investigators brought in a scientist called John Haldane, a physiologist who was an also expert in gases, to help determine the cause of the accident. He found that the blast was caused by a build-up of carbon monoxide, a conclusion that served as the catalyst for his efforts to develop a way of detecting the odourless gas before it could harm humans.

His solution ultimately became one of the most widespread (and arguably one of the most famous) forms of gas detection – the canary in the coal mine.

Let’s be honest, the practice wasn’t the most humane, but from a cold objective standpoint, there was no denying the utility of the birds. Their much faster metabolisms meant that they would get obviously sick and distressed before any humans in the area started showing visible symptoms. If a bird began chirping loudly or rattling the bars of its cage, the miners would know something was wrong. And if the canary stopped moving or making sound altogether, it was effectively the signal for an immediate evacuation.

Eventually, some miners rather thoughtfully put oxygen tanks in the cages, so the bird didn’t necessarily have to die in order to get its warnings across. Although full disclosure, it wasn’t done out of pure altruism – if the bird was revived, they wouldn’t have to halt work to go and get a new canary. Lots of people associate this practice with the Victorian era or earlier, but you might be surprised to know that in the UK, we were still employing this method up until as recently as 1986.

The 1920s – catalytic sensors and digital detectors

While canaries were undeniably useful for miners and those working in related sectors, there were still plenty of people who were somewhat uncomfortable about the idea of using them, and so new solutions were always being developed. The most notable of these occurred in 1926, when a scientist called Oliver Johnson created the catalytic sensor.

We’ll spare you the in-depth technical explanation, but essentially it works by burning the gas inside it to provide a reliable reading of gases in the atmosphere. It was a brilliant solution to a centuries-long problem, with only one minor drawback – it required continual manual operation in order to provide a reading (which is another way of saying that users always had to constantly press down a button if they wanted to know if they were being poisoned or not).

1986 saw another significant iteration on this invention, as a detector with a digital reading largely replaced the canaries (which must have come as a relief to the birds). These detectors were made from semi-conducting materials, and they worked in a broadly similar way to the catalytic sensors. The main difference was that the more advanced versions ran on batteries, so they could run for longer periods of time, and nobody had to push a button.

It was these devices that ultimately evolved into modern portable gas detection devices, just like the ones we supply here at Gas Alarms Systems. These portable gas detection devices are perfect for staff working on one-off or individual jobs in enclosed environments like sewers, while our fixed gas detection systems are designed to be installed in areas were toxic gas is more or less an ever-present concern.

We’ve been supplying these for more than 25 years here at Gas Alarms Systems, so if you’ve ever got any questions about any of our products, or you need any advice on which ones would be best suited to your applications, don’t hesitate to give us a call on 01423 862240, and we’ll be happy to see how we can help.