It is probably quite evident that there are a number of fire alarms available, and at vastly varying prices, so it may be very difficult to understand the differences lunk alarm, Ionisation and Heat alarms. This guide is aimed at taking some of that confusion away.
So what is the difference between the models?
As stated above there are three types of alarm, each with its own uses.
Optical Alarm: This type of smoke alarm usually uses an infrared beam between two points, the alarm being triggered should the beam be disturbed. In much the same way as a criminal might trip an alarm when breaking into a bank vault or museum in the movies, if the beam is broken, the alarm will go off. It detects larger smoke particles best.
Ionisation Alarm: These alarms use 2 small plates (one charged positively, one negatively) and an alpha particle source to create a constant current running across the gap between the plates. When smoke enters the chamber it interferes with this process, interrupting the charge. When the charge drops, the alarm goes off. These alarms are best at detecting smaller smoke particles.
Heat Alarms: A heat alarm will trigger if the room temperature reaches a certain level. They do not detect smoke, and are not to be used as a substitute for a smoke alarm, but should be used in assisting these alarms for greater fire detection.
Why do we need different types of fire alarm?
Different types of alarm exist due to the different types of fire. Believe it or not, fires act in different ways depending on what is burning, and is important to identify the fire as quickly as possible. Different alarms are better at discovering different fires, and choosing the right alarm for the right room could save your life one day.
Fires can be particularly smokey, often caused by the burning of papers or clothing etc, and burn rapidly, producing smaller smoke particles. The Ionisation alarms are better at detecting these fires.