Aico fire alarms, Aico smoke alarms, Aico ionisation alarms, Aico optical alarms: what is the difference?

On this website introducing the Aico fire alarms we see a lot of different types of detectors for domestic use, like the:

• Aico smoke detectors;
• Aico heat detectors;
• Aico ionisation alarms;
• Aico optical alarms;
• Aico CO alarms;
• Aico multi-sensor alarms;

and some others. Many people would ask: what is the difference between these different types of fire alarms, since it looks like, from their description, that they do approximately the same things? What is the difference between the smoke alarms and the heat alarms? What is the difference between the ionisation alarms and the optical alarms? What is the difference between the heat alarms and the optical alarms? What is the difference between the optical alarms and the smoke alarms? What is the difference between the ionisation alarms and the smoke alarms?

To make things just a little clearer than before, there are 5 types of alarms:

• Fire alarms – alarms that detect the fire in a building. These alarms are more rare and general, since there is the need to detect not only the fire that can start in a building, but even the smoke or the high level of heat.
• Heat alarms – alarms that detect the rise of the temperature, which can be due to the start of a fire, the over-heating in a room, the heat in the kitchen, etc.
• Smoke alarms – alarms that detect the rise of the smoke level in a certain venue; the smoke can be due to the fire ignited in the room, etc;
• Multi-sensor alarm – alarms that detect both the heat and the smoke in a room, using both a ionisation and an optical sensor.
• CO alarms – alarm detecting the rise of the carbon monoxide level in a room.

Concerning the types of sensors an Aico fire/smoke/heat alarm uses, there are 4 types of sensors:

• Optical sensor – optical alarms – A light beam is pulsed in the sensor chamber every 10 seconds to “look/search” for smoke. Any smoke present has to be visible to the naked eye so that the receptor may “see” it. If no smoke is detected, the alarm will remain in a standby state. When large particle smoke is detected, the light beam will be scattered onto the light receptor. This will then send an electrical signal to the IC (Integrated Circuit). If two consecutive signals are received by the IC, the alarm will sound.
  - This type of sensor can be used in the heat alarms(Aico Ei146 and Aico Ei166RC).
  
• Ionisation sensor – ionisation alarms – There is a minute(safe) radioactive (inside the sensor chamber) which ionises the air within. This causes a small current to flow in the chamber, and this current remains constant for the life of the alarm (unless some smoke particles enter into the sensor chamber). When / if smoke enters the sensor chamber, the balance of the current is disturbed. This disturbance is detected by the electronics in the alarm circuitry, and the Integral Circuit(IC) is being sent a signal. When the signal is received, the alarms sounds.
  - This type of sensor can be used in the smoke alarms(Aico Ei141 and Aico Ei161RC).
• Heat sensor – heat alarms – A thermistor (a heat sensitive resistor) is sited in the sensor chamber of the alarm. When the temperature rises, the resistance of the thermistor reduces. The IC continuously monitors the resistance of the thermistor. When this indicates that the temperature is over 54° C, the IC sends a signal to the sounder circuit. The alarm sounder then operates – the alarm rings.
  - This type of sensor can be used in the heat alarms (Aico Ei144 and Aico Ei164RC).
  
• CO sensor – carbon monoxide alarms – Detects the CO level and rings the alarm if the level is too high.
  - This type of sensor can be used in the CO alarms (Aico Ei261 and Aico Ei205).

For more information about all these Aico Alarms, visit our online store, or consult the articles concerning the Fire alarms, Fire Design, Fire Detectors, Fire safety, Aico alarms, Heat detectors, etc.