Page 704 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

* Halon or an EPA-approved halon substitute

Water cannot be used on Class B fires because it splashes the

burning liquids and such liquids usually float on water. Water
cannot be used on Class C fires because of the potential for
electrocution. Oxygen suppression cannot be used on metal fires

because burning metal produces its own oxygen.

Fire Detection Systems

To properly protect a facility from fire requires installing an
automated detection and suppression system. There are many types of
fire detection systems. Fixed-temperature detection systems trigger
suppression when a specific temperature is reached. The trigger is
usually a metal or plastic component that is in the sprinkler head and
melts at a specific temperature. There is also a version with a small
glass vial containing chemicals that vaporize to overpressurize the

container at a specific temperature. Rate-of-rise detection systems
trigger suppression when the speed at which the temperature changes
reaches a specific level. Flame-actuated systems trigger suppression
based on the infrared energy of flames. Smoke-actuated systems use
photoelectric or radioactive ionization sensors as triggers. Incipient
smoke detection systems, also known as aspirating sensors, are able to

detect the chemicals typically associated with the very early stages of
combustion before a fire is otherwise detectible via other means.

Most fire-detection systems can be linked to fire response service
notification mechanisms. When suppression is triggered, such linked
systems will contact the local fire response team and request aid using
an automated message or alarm.

To be effective, fire detectors need to be placed strategically. Don’t
forget to place them inside dropped ceilings and raised floors, in

server rooms, in private offices and public areas, in HVAC vents, in
elevator shafts, in the basement, and so on.

As for suppression mechanisms used, they can be based on water or on
a fire suppression gas system. Water is common in human-friendly