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Tips & Tricks Blog


How Do Smoke and Carbon Monoxide Detectors Work?

10/04/17

detector

Two of the most important electronics in your home are also among the simplest. The smoke detectors that provide critical fire warnings and the carbon monoxide detectors that protect you from an invisible threat are extremely basic, and that’s part of what makes them so reliable, compact and inexpensive.

Safety Is Everything

It goes without saying that these are essential safety devices. Early warning against house fires can give you and your family time to escape to safety or extinguish small fires before they can spread. And when it comes to carbon monoxide, detectors are even more crucial -- carbon monoxide is odorless, tasteless and colorless, and can leak into your home from hidden sources such as undetected cracks in your furnace’s heat exchanger.

Because they’re so important, many building and safety codes require that these detectors be installed in occupied structures and replaced upon expiration. If you’re unsure whether your home is up to code, call an electrician or do your own research into your local laws. In many jurisdictions, residential homes are required to have at least one working smoke detector on each floor of the home, plus one more outside each bedroom. Carbon monoxide detector regulations are more varied, but are often required in homes with attached garages, fireplaces or natural gas appliances.

Upkeep is important as well -- you should test all your detectors and replace the backup batteries twice per year. This is a great time to check the sticker on the back and confirm the expiration date so that you can plan ahead for replacement.

Where There’s Smoke, There’s Fire

There are two common types of smoke detectors, and each has a particular advantage over the other.

One type is the photoelectric detector, which uses a beam of light to detect the presence of smoke in the air. This light is projected through a small chamber, and the “eye” that can see the light is pointed toward the side of the beam. When smoke particles float into the beam, the light reflects off of them and toward the eye, which then sends an electronic signal to sound the alarm.

The other common type is the ionization detector, which uses a tiny amount of radioactive material to ionize the air inside an electrified detection chamber. As smoke enters the chamber, the particles interrupt the ionized electronic charge, creating a drop in voltage. That change sends a signal to activate the alarm.

Photoelectric detectors are best at detecting smoldering fires that produce lots of smoke, and ionization detectors have the upper hand with small, flaring fires that produce less smoke. Some of the most sophisticated models use both technologies. If you want to cover all your bases, choose these combo detectors or use a combination of both types throughout your home.

See the Unseeable

Carbon monoxide detectors are available in three types: biomimetic, metal oxide semiconductor and electrochemical.

Biomimetic detectors feature a small chamber filled with a gel that mimics carbon monoxide’s effects on blood. When the gel contacts carbon monoxide particles, it changes color, and that color change is detected by an electronic sensor that triggers the alarm.

With a metal oxide semiconductor detector, a small silica chip is what interacts with carbon monoxide in the atmosphere. This interaction causes a drop in the current flowing through the chip, similarly to the way ionization smoke detectors work. When the voltage drops, the alarm sounds.

The most sensitive carbon monoxide detectors use electrochemical sensors that consist of electrodes submerged in chemical baths. These are less commonly used for household safety but have a variety of industrial applications.

Do you need new smoke or carbon monoxide detectors hardwired into your home’s electrical system? Don’t wait when safety is on the line; call your local Mister Sparky today to discuss your options and schedule an appointment.



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