No Smoke Without Flames? How Smoke Alarms Work

The modern smoke alarm is very much part of our everyday lives, from the familiar white circular unit stuck to our ceilings to more robust detectors in our workplaces and factories. It's easy to assume that any old smoke detector will do for any position, but that's far from the truth. There are three main types of smoke detectors, designed to detect various types of fire.

Ionisation smoke alarms

Ionisation smoke alarms are the best choice for areas with a ready source of combustible materials, and therefore at risk from burning fires with flames. This could be anything from a warehouse full of supplies to your lounge furniture!

Ionisation smoke detectors detect very small particles, invisible to the human eye, and hence can detect the debris rising from flames very early on. However, this also makes them unsuitable for kitchens, as normal cooking releases particles that set the alarm off.

How Ionisation Smoke Detectors Work

As they say in the advert, here comes the science! Inside each alarm's ion chamber is a very small source of radioactive, ionising radiation. (Don't worry, it is very small and well within safety guidelines.)

This creates electrons with a negative charge, and positive-charged atoms. Their movement within the chamber creates a small but steady electrical current. Smoke particles entering the chamber disrupt this current, which then falls, triggering the alarm.

The practical result of this is that even when you can't see fire-born particles or smoke in the air, an ionising smoke alarm can! Fire Protection Online offer the Kidde 123/9hi mains ionisation alarm, with a six-year warranty and backup battery, at a very visible 22% off RRP.

Photoelectrical or Optical Smoke Alarms

As their name implies, optical smoke detectors 'see' visible particles and react accordingly. Inside each photoelectrical smoke alarm is a red LED light, positioned opposite a light-detecting photosensitive cell. If smoke enters the light chamber, it scatters the light. The photosensitive cell detects this, and the alarm sounds.

Since this type of alarm responds to visible particles, a photoelectrical or optical smoke alarm is best at detecting slow-smouldering fires that give off smoke and ash. It can also be placed next to a kitchen or bathroom, as steam or invisible cooking particles will not affect the alarm.

At Fire Protection Online, Kidde's 223/9hill optical 230v mains smoke alarm with its long-life 10-year battery backup costs just under £20 + VAT.

Heat Alarms

Heat alarms only respond when temperatures rise above 57 degrees C (that's 135 degrees F), and many new homes built since the year 2000 have these alarms already installed in their kitchens.

Heat alarms are not only useful in the kitchen but also in dusty areas, such as unconverted lofts or basements. In addition, you can install a heat alarm to protect your garage, as regular smoke alarms will be set off by your car's exhaust fumes every time you back in!

Fire Protection Online sell the Kidde 323/9hi mains operated heat alarm with battery backup with a red-hot discount of over 30% on the RRP.

What Type Of Smoke Alarm Should I Install In My Premises Or Home?

For the best protection, you should install a combination of all three types, according to the risks posed. Any kitchen area should always have a heat alarm fitted. In your home, the best rule is to place a smoke detector in each bedroom, plus one in the hallway, landing, and any additional rooms at risk. Also, fit a heat alarm in your kitchen.

Smoke Alarms: 10 Year Battery 'Fit And Forget' Models

A smoke alarm with a dead battery is a complete waste of time. By fitting Kidde smoke alarms with integral 10 year batteries from Fire Protection Online, your smoke alarm will give you up to ten years of continuous protection against fire in your home or small office.

When the unit is almost at the end of its life, it will give a 'chirp' warning. All you have to do is remove it and replace it with a new one - it's as simple as that!