Smoke alarms are incredibly important for safety, but they come in a variety of different technologies, and customers may not be fully aware of which type to get. How do different smoke detecting technologies work, what challenges do they face with consumers, and why is it imperative to get critical information to customers?

What smoke detecting technologies exist?

Smoke detectors are a critical piece of infrastructure that can, and often do, mean the difference between life and death. Detecting a fire as early as possible can give precious moments for those nearby to either prevent the fire from getting worse or time to escape with others. But not all fires are the same, and different fires need to use different detecting technologies to provide adequate time to escape.

The most common type of fire alarm found in domestic properties is the ionising radiation variety. These utilise a small piece of americium that is placed in the path between two electrodes. Under normal conditions, the alpha-emitter ionises the air and allows a small electric current to flow between the two electrodes. However, a fire that produces thick particulates will block the electrical current, thus detecting the fire.

The second type of fire alarm is photoelectric and works on the principle that even fine smoke hinders light transmission. Essentially, a laser is shone onto a small mirror, which reflects the light onto a sensor.

Under normal conditions, the beam is unaffected by the air, and thus the output of the sensor is at its maximum. The presence of smoke reduces the beam's intensity, which translates to the detection of smoke. While not a smoke detector, fire detectors also play an important role in not reacting to smoke. Instead, these devices use IR sensors that react to hot flames over a period of time. Thus, they do not trigger when detecting a sudden flame but will instead react after a minute or so from the first detection.

What challenges do smoke alarms face?

Due to their life-saving requirements, smoke alarms are designed to be highly reliable, and newer versions now have two power sources; the mains for normal operation and batteries for times of power cuts. However, smoke alarms are only as good as their owners, and smoke alarms are very often removed due to their nuisance when beeping falsely.

However, recent statistics on fire alarm use show that users worldwide could be vulnerable to the changing nature of fires. According to The Signal, modern fires often produce smouldering fires that release thick smoke but very few particulates. This means that ionisation smoke alarms will be less effective in a modern fire, and information regarding smoke alarm technology is rarely placed on smoke alarm product packaging.

While the data presented was for a district in Canada, it is still worrying that only 10% of households in that area use photoelectric fire alarms while the rest continue to rely on ionisation. Considering that the UK is home to many older buildings and that public information on smoke alarm technology is virtually non-existent, it would be safe to assume that there are also many vulnerable properties from modern fires.

Why it is so important to get the correct information to customers?

In the case of smoke alarms, it makes sense for homeowners to have multiple detectors, including ionisation, photoelectric, fire, and CO alarms. But when purchasing smoke alarms, the only real clue as to the technology used is a small radioactive symbol on the back of the packaging, which only technically minded individuals recognise.

As an engineer, it is very tempting to talk about standard features of a product such as dimension, material, and weight, but any information that may be critical to its operation must always be given priority. For example, new smoke alarm packages should make it clear to the user what type of smoke alarm it is and how it should be used with other alarm technologies.