BEFORE fire breakout, the light emitted from the light source is not detected by the photo sensor.
When smoke particles enter the chamber, some of the light is scattered toward the photo sensor.
DURING fire breakout, as the amount of smoke particles that enter the chamber keep on increasing, more incident light is scattered toward the photo sensor.
When the concentration of particles reaches a predetermined threshold, it will trigger the alarm and sends data message to the system control panel for processing.
Light Scattering Smoke Detector
Ionized Smoke Detector
Detection
Has a light source projecting its beam into a light trap. When the smoke enters, the light will
be strike by the smoke and then reflect onto the photoelectric cell & continuous generate the
alarm system.
Have an ionization chamber which consists of 2 electrodes/ electrical plates. When smoke enters the chamber, smoke particles attach to the ions
and disrupt the flow of ions. Therefore, the decline of
flow of current activates the alarm.
Types of Fire it detects
Smoldering fire and dense smoke.
Good for fast flaming fires with less visible smoke.
Sensitivity• Less sensitive to steam.• However, false alarm may occur due to insects or dust.
• Less likely to cause false alarm due to insects or dust.• However, it can easily cause disturbing alarm if the installation of detectors is close to the stove.
Price Slightly expensive. Slightly cheaper.
SafetyDoes not contain any radioactive materials.
It contains small amount of radioactive material.
1) It is not harmful towards human health.2) Its detection towards smoke is much
faster than ionization smoke detector.3) It works best in an enclosed area.4) It meets the requirement from the Fire
and Rescue Department (BOMBA).
Reasons :
Conclusion & Suggestions
We will never know what type of fire or other circumstances that may happen. Hence, we must always be careful and stay alert.
Our group suggests that the university should think about installing smoke detectors in every classroom for added safety.