Types of Smoke Alarms

One of the most important installations in buildings for safety against fire is the smoke alarm. Various types of smoke alarms became widely available in the United States since the 1970s. Once they were generally available, prices fell and their sale also increased rapidly. By 1991, almost 88% of the houses in the US had smoke alarms or fire alarm systems. Since then the number of fatalities due to fire related accidents have dropped by half.

What are Smoke Alarms?

Smoke alarms are self-contained devices that can detect fire or smoke and set out an alarm for the occupants of a building to evacuate its premises. Smoke alarms detect fire at an early stage. This gives individuals ample time to leave the building that has caught fire. Hence, installing smoke alarms helps to reduce casualties to a large extent and ensures fire safety. Smoke alarms that are also known as smoke detectors are typically enclosed in a circular disk-like plastic enclosure and are fitted to the ceiling. However, the shape may vary according to the make and the company.

Types of Smoke Alarms

There are mainly three types of smoke alarms available in the market. They are:

Ionization Smoke Alarms: These smoke alarms are sensitive to small particles of smoke caused due to fast flaming fires like oil or fat fire caused in the kitchen. These are sensitive to smoke particles that are too small to be detected, and sets out an alarm much before the smoke gets too thick. However, they are less sensitive to slow and smoldering fires that give off lots of smoke before the flaming fires are caused. These are the most widely available smoke alarms and are also inexpensive. However, they are quite prone to setting off false alarms.

Optical Smoke Alarms: These alarms are more expensive that the ionization smoke alarms. However, the advantage that these alarms have over the ionization alarms is that these are less prone to sending out false alarms. They do not react to steam or cooking fumes produced in the kitchen and steam in bathrooms. They are effective in detecting smoke particles produced by slow, smoldering fires, that may be caused to due to burning of foam-filled upholstery or PVC wiring insulation. However, optical alarms are slower in detecting fast flaming fires.

Combined Smoke Alarms: As the name suggests, these smoke alarms use the technology of both the ionization as well as optical smoke alarms. Hence, they can detect a fast-flaming as well as a slow, smoldering fire.

Additional Features

To prevent the smoke alarms from setting off false alarms, certain models have a provision of 'silencing' them by pressing a button. Once this button is pressed, there is some sort of indication like a small red light glowing to let the user know that it is in the 'silent mode'. However, once there is thick smoke due to fire, these alarms come out their silent mode and the alarm rings out loud.

Some smoke alarms are interconnected so that smoke detected by one smoke alarm in one room activates the others installed in other areas of the house. There are smoke alarms for people with special needs. For example, for people with hearing disabilities, there are alarms with emergency lights that flash once they detect smoke.

Power for the Smoke Alarms

Smoke alarms may be run on batteries, mains electricity or by a combination of both. The batteries need to be replaced every year. However, there are smoke alarms that come with batteries that can last for almost 10 years. Although these are more expensive than the others that run on ordinary batteries, they can save the cost and trouble of replacing batteries each year. Although a mains-powered alarm eliminates the use of batteries, it is important to install one that has a power back up so that you are informed of fire even when there is a power cut. Also get a qualified electrician to fit such alarms.

Smoke alarms are an important component of home security systems.There are a many different types of smoke alarms to choose from. Which ones should be installed depends upon the type of fire that is most likely in the different rooms of a home or building. Installing the right type of smoke alarm is very important. However, what is most important is to ensure that the smoke alarms are always in proper working condition.