SecurityArena

Fire

Fire detectors

• Smoke activated. Normally a photoelectric device. These are good for early-warning devices as can be used to sound a warning alarm before the suppression system activates.
• Heat activated. Rate-of-rise temperature sensors and fixed-temperature sensors. Rate-of-rise temperature sensors usually provide a quicker warning than fixed-temperature sensors because they are more sensitive, but they can also cause more false alarms.
• Flame activated. Senses the infrared energy
• Automatic Dial-up Alarm. Call the local fire station to report detected fire.

Fire suppression

Portable extinguishers should be located within 50 feet of any electrical equipment and located near exists.

Fire Components

Heat, Fuel, Oxygen and chemical reaction are four fire components. A fire suppressant tries to suppress one or more of these components to control the fire.

• Water suppresses the temperature required to sustain the fire.
• Soda Acid suppresses the fuel supply of the fire.
• CO2 suppresses the oxygen supply required to sustain the fire.
• Halon  suppresses the combustion through a chemical reaction.

Type of Fires and Suppressant

Note: Halon as a fire extinguisher has been banned in most countries due to the Montreal Protocol. Approved replacements for Halon include FM-200, NAF-S-III, CEA-410, FE-13, Water, Inergen, Argon and Argonite.

Water Sprinklers

These are simpler and less expensive than halon and FM-200 systems but can cause water damage. In an electrical fire, the water can increase the intensity of the fire, because it can work as conductor for electricity. Electricity must be turned off before the water is released.

• Wet Pipe (Close head Systems). Always contain water in the pipes and are usually discharged by temperature control level sensors.  Water may freeze in colder climates.
• Dry Pipe. The water is in a “holding tank” and held by a valve until a specific temperature is reached. There is a time delay between the predefined temperature being met and the release of water.
• Preaction. Combine the use of wet and dry pipe system. Water is not held in the pipes and is only released into the pipes once a predefined temperature is met. Once this temperature is met, the pipes are filled with water, but it does not release right away. A link has to melt before the water is released from the sprinkler head itself. It allows reaction time to counter to false alarms.
• Deluge. The same as a dry pipe system except the sprinkler head is wide open to release a large amount of water. It is not usually used in data centers.