Page 706 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

systems. However, gas discharge systems should not be used in
environments in which people are located. Gas discharge systems

usually remove the oxygen from the air, thus making them hazardous
to personnel. They employ a pressurized gaseous suppression
medium, such as CO2, halon, or FM-200 (a halon replacement).

Halon is an effective fire suppression compound (it starves a fire of
oxygen by disrupting the chemical reaction between oxygen and
combustible materials), but it degrades into toxic gases at 900 degrees

Fahrenheit. Also, it is not environmentally friendly (it is an ozone-
depleting substance). In 1994, the EPA banned the manufacture of
halon in the United States. It is also illegal to import halon
manufactured after 1994. (Production of halon 1301, halon 1211, and
halon 2403 ceased in developed countries on December 31, 2003.)
However, according to the Montreal Protocol, you can obtain halon by
contacting a halon recycling facility. The EPA seeks to exhaust existing
stocks of halon to take this substance out of circulation.

Owing to issues with halon, it is often replaced by a more ecologically
friendly and less toxic medium. The following list itemizes various
EPA-approved substitutes for halon (see
http://www.epa.gov/ozone/snap/fire/halonreps.html for more
information):

FM-200 (HFC-227ea)

CEA-410 or CEA-308

NAF-S-III (HCFC Blend A)

FE-13 (HCFC-23)

Argon (IG55) or Argonite (IG01)

Inergen (IG541)

Aero-K (microscopic potassium compounds in aerosol form)

You can also replace halon substitutes with low-pressure water mists,
but such systems are usually not employed in computer rooms or
electrical equipment storage facilities. A low-pressure water mist is a

vapor cloud used to quickly reduce the temperature in an area.