Fire Gas Detection Security

In Plants I have worked We dont have equipment or unit shutdown if Combustiable /Toxic Gas has been detected ,This alarm is directed to Area Siren upon activation of High level

Regards

Jose

do you mean methane ?

http://www.google.co.uk/search?q=what+is+fire+gas&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&redir_esc=&ei=9Q_bS_37GZH20gSHqayRBg

Typically;

Fire detection systems are used for alarming and for the initiation of extinguishing systems (deluge systems, inergen, FM 200 systems etc in control buildings and so on) and for the isolation of dampers in HVAC distribution ducts.

Gas detection systems are used for alarming, for the manipulation of HVAC systems i.e. switching from fresh air intake to recycle and for the start-up of emergency breathing air systems.

You should check the project specifications which will give the design intent and requirements of the systems which must be satisfied and list the applicable standards to be referenced. Also important would be any mandatory requirements from the AHJ in your area.