Fire Detectors Types And Selection -

Fire Detectors types and selection

2017-03-24

There are many types of fire detectors. These detectors can predict fire from change of environment. Different situation can induce fire with different cause. So, the change of environment is different as well. Fire detectors are designed to sense defined environment change such as heat, smoke. So, it is required to select different fire detectors for different situation.

Smoke Detectors

Smoke Detector is suitable for situation of much smoke, little heat and flame produced at initial stage of fire. The following properties should use spot-type smoke detectors.

  • Restaurants, hotels, school buildings, office hall, bedroom, office, etc.
  • Computer room, communications room, a movie or television show room
  • Stairs, walkways, elevator machine room, etc.
  • Library, archives, etc.
  • The place where there is with danger of electrical fire

TYPES OF SMOKE DETECTORS

There are two types of smoke detectors. They are photoelectric smoke detector and ionization smoke detector. Generally, photoelectric smoke detector is popularlly used cause of no Radiation hazard compared to ionization smoke detector. But these two types smoke detector working effect is different at different situation. So, there is the rule to select the correct type smoke detector.

Where the ionization smoke detector is not suitable

  • Relative humidity is often greater than 95%
  • Airflow velocity is greater than 5m/s
  • There is a large amount of dust, water mist retention
  • Corrosive gases may be produced
  • Under normal circumstances there is smoke retention
  • Alcohols, ethers, ketones etc. organic substances is produced

Where the photoelectric smoke detector is not suitable

  • Black smoke may be produced
  • There is a large amount of dust, water mist retention
  • Steam and oil mist may be produced
  • Under normal circumstances there is smoke retention

Heat Detector

Heat Detector is suitable for situation of rapid developing fire where a lot of heat is produced. The following properties should use heat detectors.

  • Relative humidity is often greater than 95%
  • Smokeless fire
  • There is a lot of dust
  • Under normal circumstances there is smoke and steam retention
  • Kitchen, boiler room, generator room, drying workshop, etc.
  • Smoking room, etc.
  • Other places such as halls and public places where smoke detector is not suitable for installation

Flame Detector

Flame Detector is suitable for situation of rapid developing fire where strong flame radiation is produced and with few smoke, heat. The following properties should use flame detectors.

  • In the fire, there is a strong flame radiation.
  • Liquid burning without Smoldering stage of fire
  • Need to react quickly to the fire

Where the flame detector is not suitable

  • Flameless fire may occur
  • Smoke spread before the fire
  • The detector lens is easy to be contaminated
  • The detector's line of sight is easy to be blocked.
  • Detectors are subject to direct or indirect exposure to sunlight or other light sources.
  • There are fire operations and X-ray, arc and other effects in normal circumstances

Combustible gas detector

Combustible gas detectors shall be selected for the situation where flammable gas or liquid vapor is used, produced or accumulated. The following properties should use flame detectors.

  • Where Pipeline gas or natural gas, LPG is used
  • Gas station and gas meter housing and storage of liquefied petroleum gas tank place
  • Other places where combustible gases or vapors may be spreaded
  • CO detector should be used at where carbon monoxide may be produced

Combination of smoke detector, heat detector, flame detector (same or different types) should be used at places where single detector can not effectively recognize the fire. For fire alarm system with linkage control device, automatic fire extinguishing system, the combination of different types fire detectors should be used as well.


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