Photoelectric Vs. Ionization Smoke Detectors

With a wide range of smoke detectors available in the market, deciding which one would be ideal for your home can be a tough task - especially when you have no idea about what smoke detectors are and how they work. To cut it short, smoke detectors aka smoke alarms, as their name suggests, are devices which detect smoke particularly as an indication of fire and alert you by triggering the fire alarm. Smoke detectors for home use are relatively small, and run on 9-volt battery or 120-volt current. Of the different types of smoke detectors available, the two most common types are photoelectric smoke detectors and ionization smoke detectors - both of which are poles apart when it comes to working mechanism.

Photoelectric Smoke Detector Vs. Ionization Smoke Detectors

This may come as a surprise for many, but neither photoelectric smoke detectors nor ionization smoke detectors are efficient enough to detect all types of fires that are likely to occur. As we mentioned earlier, each of these devices work on a different principle and therefore are likely to respond to different conditions differently. Before we get to the detailed comparison of these smoke detectors, let's go through some general facts about each of them individually to get a better understanding of how these smoke detectors work.

Photoelectric Smoke Detectors
Photoelectric smoke detectors, also known as photoelectric-type smoke alarms, resort to a light emitting diode and the presence of a light sensor in the sensing chamber to detect smoke or fire in the surroundings. The light beam, in this case, is angled away from the sensor. When suspended combustion particles enter the device, they tend to scatter the light beam which is deflected towards the sensing chamber wherein it comes in contact with the light sensor and triggers the alarm.

Ionization Smoke Detectors
Ionization smoke detectors, also known as ionization-type smoke alarms, are typically characterized by the presence of a small amount of radioactive material within the device. This radioactive material ionizes the air in the sensing chamber, and makes it conductive, thus facilitating current flow between the two charged electrodes present within. When the device is subjected to smoke, it tends to disrupt the flow of ions, thus reducing its conductivity which, in turn, hampers the current flow and triggers the alarm.

Which is Better: Photoelectric or Ionization Smoke Detector?
Determining which is better of the two in not an easy task with each of them having a specific area wherein they work the best. Experts are of the opinion that photoelectric smoke detectors are ideal for living rooms, bedrooms and other such rooms wherein combustion of matter is more likely to create smoldering smoke instead of flames. On the contrary, ionization smoke detectors are known to detect flaming fires more efficiently, as a result of which they are considered to be ideal for rooms wherein highly combustible substances- such as paper and flammable liquids, which are known to create flames exist in plenty. You need to take these attributes of each of the two smoke detectors when choosing one for your home.

Alongside all these points of distinction in photoelectric and ionization smoke detectors comparison, one also has to take into consideration the nuisance alarm factor. A study at the National Institute of Standards and Technology (NIST) in the United States revealed that the nuisance alarms in residential settings are most often attributed to aerosols produced from a range of activities right from cooking to burning a candle, the concentration of these aerosols produced, the location of smoke detector, etc. Ionized smoke detectors in particular are notorious for nuisance alarms in response to such aerosols which are produced and released in the surroundings even before noticeable smoke is produced.