The system consists of an electronic alarm panel connected to detectors that are located in strategic points within the room and a gas cylinder containing FM 200 re-agent which can be located
within or outside the room but whose gas is piped direct to the center of the protected zone and has a self activating valve known as actuator.When smoke is detected, an alarm signal goes to the
electronic panel, which then activates both audio and visual alarms and indicates the zone where the alarm is detected. This is the first stage (or first knock). On detection of heat another alarm
goes to the panel, which simultaneously generate three signals: One is visual and shows the zone where problem exist, the second is audio, while the third is an instruction to the actuator to
discharge the gas. This is the second stage (or second knock), hence the name 2- knock system.FM-200? is a colourless, liquefied compressed gas. It is stored as a liquid and dispensed into the
hazard as a colourless, eclectically non-conductive vapour that is clear and does not obscure vision. It leaves no residue and has acceptable toxicity for use in occupied spaces at design
concentration. FM-200? does not displace oxygen and therefore is safer for use in occupied spaces without fear of oxygen deprivation.The FM 200 gas is the replacement for the Halon and other inert
gases used in the past to control fire, which were later discovered to be harmful to the Ozone layer. The volume of the gas (FM 200) is calculated on the basis of percentage / volume in the air
that will make the air non-supportive to combustion. At approx 7%/ volume, it has been shown that FM 200 will extinguish fire fast especially if fresh air is not allowed to enter and dilute the gas
in the envelope. To ensure this, all the windows shall be covered with Gypsum Board. At the 7% volume, it has been established that there is no danger at all to human beings breathing in the air.
Other feature that strongly recommends the FM 200 includes its ability not to leave any residue (not even dust) after discharge.