What is the purpose of a gas detector in a fire alarm?

Gases are a tricky thing to detect on your own – many of the most dangerous gases are the least perceptible, leaving no vapor trail, scent, or taste. Toxic and combustible gases are especially dangerous – oftentimes, the presence of such gases can completely evade the average person until it’s too late; an errant spark causing the gas to ignite and triggering an explosion, or the symptoms of toxic gas inhalation not being present until it’s already too late. Thankfully, the addition of gas detectors to your existing fire alarm system can ensure your safety from these dangerous gases from affecting you in a negative way.

Smoke and carbon monoxide aren’t the only dangerous gases that can affect a home. Natural gas leaks and other combustible gases can enter a home through a number of means, but most likely, through appliances that use these types of gases. By investing in gas detectors, you can be constantly aware of the air quality in your home or business without the worst case scenario taking place to find out about it.

How does a gas detector work?

How a gas detector works is dependent on whether the detector is built to detect combustible or toxic gas. Generally, catalytic and infrared sensors detect combustible gases while electrochemical and metal oxide semiconductor sensors detect toxic gases. How each of these sensors work will be explained below.

How does an electrochemical sensor work?

Electrochemical sensors work to detect toxic gases, typically carbon monoxide, chlorine gas, and nitrogen oxides. Within these sensors is a sensing electrode, a counter electrode, and an ion conductor in between. When toxic gas enters the sensor, it will contact the sensing electrode. This causes a reaction in the ion conductor to the counter electrode. The current between these electrodes is then used to measure the level of toxic gas present in the air.

How does a metal oxide semiconductor work?

Also used for detecting toxic gases such as carbon monoxide, sulfur dioxide, hydrogen sulfide, and ammonia. Metal oxide semiconductors work using a film made of metallic oxides that are sensitive to gas; typically tin dioxide. This film is heated, causing it to produce electrons that flow through the material, which generates a current. When air is displaced by toxic gases, the current increases, and this current is once again used to measure the levels of toxic gas present.

How does a catalytic sensor work?

Many combustible gas detectors are catalytic sensors. Useful for detecting combustible gases like hydrocarbons, catalytic sensors work via catalytic oxidation. When combustible gas enters the sensor, it comes into contact with a catalytic surface, oxidizing it and increasing the heat, increasing the resistance of the wiring within the sensor. The change in resistance is then used to measure the presence of combustible gas.

How does an infrared sensor work?

Infrared sensors are also used to detect combustible gases. Within an infrared sensors are a series of transmitters; sending and receiving light sources within the sensor. These infrared lights can be disrupted by the presence of combustible gas, interfering with the light. By sensing how much light is being received from the light source, the infrared sensor can then determine not only if gas is present, but what kind of gas is present based on how much that specific gas is interrupting the light.

Knowing which gas sensor is right for you comes down to environment and concerns. Properties that deal with potential gas leaks  – those heated with natural gas for example – should be aware of whether dangers brought on by combustible gas or toxic gas are the major concern. Environmental restrictions may also take place with certain types of sensors – catalytic sensors don’t work in low or zero oxygen environments, and electrochemical sensors require humidity to function. Be sure to keep environmental restrictions in mind when it comes to installing your gas sensors.

How to properly place gas sensors during install

The first thing to do when preparing to install your gas sensors is taking inventory of any and all potential gas hazards on the properties. When investigating, look for two things: where gas may be flowing from upon release, and places that may be endangered during gas leaks. Confined spaces like crawl spaces and stairwells can be a massive danger during a gas leak. Best places to install your gas leak detectors include areas of the property that can release these gases – appliances like ovens and stovetops, fireplaces, space heaters, and of course, your home’s heating system if you run on natural gas. Gas detector manufacturer Honeywell recommends placing these detectors higher than all doors and windows, about six inches from the ceiling and within ten feet of the appliances it’s meant to monitor.

Gas is a difficult thing to consistently track; your property’s airflow could pose a concern if said airflow could move the gas leak more quickly to other rooms. Keeping gas detectors plentiful across the property will help prevent this. It’s also important to keep your gas detectors away from windows, as the fresh air moving through could interfere with the device and give an inaccurate reading.

Why you should include gas sensors in your alarm system

Gas is hard to detect on its own. Most are invisible, without any discernable odor or taste. This difficulty in noticing them has led to plenty of preventable damages, injuries, and at worst, deaths. Gases can build up to such a point that being exposed to them for short periods can start to have a negative effect on you, whether the gas begins poisoning those on the property, or a small spark setting off an explosion from the combustible gas. You should include gas sensors in your alarm system in order to best prepare for – and prevent – the worst. Gas detectors can inform you of the presence of lethal gases that may be unnoticeable until symptoms of poisoning set in, or a small spark causes an inferno. This then allows you and any other residents to take immediate action, to evacuate and contact authorities to deal with the gas leak.

Fires aren’t the only thing you should have an active detector for. Smoke detectors will only be able to sense smoke and likely won’t be much help in the event of microcarbons or natural gas leaking into your property. Only gas detectors can do that. Proactive and preventative thinking is the most important way to protect you and your property and those on it from damage caused by gas leaks – consider what gases may be on your property, what appliances or machinery uses them, and where it could potentially leak into. Staying safe from various deadly gases is as easy as having properly installed gas detectors on your property – another service offered with Cunningham Security.