Which smoke detector to use

When no smoke interferes with this beam, the receiver accepts the beam at a specified voltage level, but when smoke interferes with the beam, the infrared light reaching the receiver drops below the predetermined sensitivity level of the receiver, initiating a signal. Beam-type photoelectric detectors can be sensitive to voltage variations, dirt on the lens or mirrors, building vibration, and insects.

Light scattering smoke detectors Tyndall Principle. The Tyndall-principle photoelectric detector is of the spot-type and detects smoke by sensing the light reflected by smoke particles. The smoke particles enter the detector and reflect or scatter light from a small lamp, or LED, in the device. Some of that reflected light strikes a photocell that produces an electrical current.

As the number of particles increases and more light strikes the photocell, the intensity of the electrical current increases. Some of the findings include:. Additional study is needed regarding photoelectric alarm response in flaming scenarios. There was some push back from various groups following the release of the above report; thus, the Technical Committee commissioned a second task group to re-review the information.

As expected, ionization detectors provided earlier warning to flaming fires, while photoelectric detectors provided earlier warning to smoldering fires.

Consistent with prior findings, ionization-type alarms provided somewhat better response to flaming fires than photoelectric alarms, and photoelectric alarms provide often considerably faster response to smoldering fires than ionization-type alarms.

The authors developed a fault tree analysis for detector reliably predicative modeling. In short, the single greatest cause of detector failure does not have to do with the type of detector, but with a lack of power to the detector.

Home fatal fires, day or night, include a large number of smoldering fires and a large number of flaming fires. You cannot predict the type of fire you may have in your home or when it will occur. Any smoke alarm technology, to be acceptable, must perform acceptably for both types of fires in order to provide early warning of fire at all times of the day or night and whether you are asleep or awake.

In general, photoelectric detectors respond better to a smoldering fire and ionization-type detectors to a flaming fire. To address the differences in detector types, nearly all of the major manufacturers offer dual ion and photo sensor detectors. Additionally, most risk control specialists recommend that carbon monoxide detectors also be installed to ensure that all possible combustion products are detected.

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Smoke detectors are installed in apartments and houses all around the country and save lives, yet most homeowners are not familiar with how these devices work. There are two main types of smoke detectors. Most homeowners don't know that smoke detectors come in two types: ionization smoke detectors and photoelectric smoke detectors.

At this point you might wonder why anyone even bothers with knowing the difference. While it may not be make for the most riveting article to read, knowing how ionization and photoelectric detectors work differently can potentially save your life one day. This type of smoke detector uses ionized particles to detect the presence of smoke.

Each ionization smoke detector holds a tiny amount of radioactive material, which is placed between two electrically charged plates. The reaction between these components causes the ionization of air. This in turn creates a current between the two plates.

When smoke gets into the detector, the current is disrupted and the alarm is triggered. Ionization smoke detectors are know to work better with flaming fires—these are fires with aggressive, open flames. Their effectiveness with other types of fires, such as smoldering fires, isn't as great.

That is why we have another type of smoke detector. The second most popular type of smoke detectors are photoelectric detectors. Unlike ionization detectors, these detectors use a light source and a light sensor to detect smoke. Once the smoke enters the detection chamber, the smoke particles block the light beam and partially reflect light onto the sensors. This in turn trips the alarm. Since many smoldering fires fill the room with dangerous fumes and smoke way before progressing to the open-flame stage, these type of detectors tend to be better at early detection.

The only real way to improve your safety is to install both types of smoke detectors in every room where a smoke detector might be necessary. The truth is, you simply can't predict which type of fire you may encounter. A visual guide to the differences between both smoke alarm types. Ever since the s, all smoke detectors have become affordable enough for almost every homeowner.

Now that we have covered the main types of smoke detectors, we need to touch upon different ways of supplying power to the detectors.

There are generally two options, both of which work, but one of option is definitely a safer and more reliable choice. Most detectors out there are powered by batteries. Fire alarms have different sensors to detect different fire types.

Some alarm sensors react to heat and some to the physical smoke created by a fire. By fitting the right type of alarm sensor you will avoid nuisance alarms and get the best protection. Here is our guide to choosing the right alarm for each area within a property.

The two houses below show rooms that are colour coded to show which sensor types are best suited to each area of a typical property. A multi-sensor alarms contains both an optical and heat sensor to detect both smoke and heat. As the alarm intelligently monitors both sensors, the risk of nuisance alarms is virtually eliminated. Alarms containing optical sensors use an infra-red beam to detect smoke and are less prone to false alarms from cooking fumes if fitted in the hallway next to kitchens.

Alarms containing heat sensors only detect changes in temperature using a thermistor.