Fire Alarm Systems Basics

Components

• Every fire alarm system contains certain main components. These include the keypad, the control panel, the zones, the input devices and the output devices.

  The control panel receives the signals, monitors them and notifies you in case of any danger. This is also where the power supply is located. The keypad consists of buttons where you key in passwords for setting and disengaging the device. The zone feature is set to react in a certain way to disturbances. For example, a zone detecting heat may respond by activating the sprinkler system within that zone, leaving all other zones unaffected. The input devices include the smoke and heat detectors and the output devices include the audio aspects (either a vocal or horn warning).

Smoke and Heat Detectors

• The three main types of smoke detectors include optical, beam and ionization. Optical detectors work by a red beam reflecting off of the smoke particles. Beam detectors work by using a transmitter and receiver as well as a red beam to detect an interruption within the normal air flow. Ionization detectors detect charred smoke particles that are affecting airflow as they pass through two electrodes.

  The two main types of heat detectors are those that are based on rise of temperature and those that are based on fixed temperature. The rate of rise heat detectors detect sudden changes in temperature. Fixed temperature detectors operate according to the set fixed temperature; once this is reached, an alarm sounds.

Placing Detectors

• To place fire alarm detectors you need to know the radius of them. Smoke detectors have a coverage radius of 7.5 meters while heat detectors only have a 5.3 meter radius. You should install enough detectors to reach every part of a room for the best protection. Detectors also need to be 500 mm away from walls and 1 meter away from air conditioners to work properly.

  If there is an obstacle that comes up to more than 10 percent of the height of the ceiling, then treat that obstacle as a wall and place your detectors to accommodate for this. Check for any voids in passageways that you should cover.