Answer / welcome4ujd

providing all details here is difficult, i will try to give
some basics.

The Fire and Gas system (FGC) is designed to give the
earliest possible warning and location of:
a) A fire in its initial stage.
b) A flammable gas leakage or accumulation up to the
lower explosive limit (LEL%).
c) Any toxic gas likely to be present up to the
occupational exposure limit (OEL).
the architecture is
Detectors(input)--detector interface module--Fire and gas
control panel--outputinterface module--interface relay --
output devices
Description of the items :
1- The detectors are Manual Call Points, Fire
Detectors or Toxic Gas Detectors.
2- All incoming detector field circuitry interface
with the Fire & Gas control panel (F & GCP) by means of a
detector interface modules.
3- The F&GCP (Fire & Gas control panel) looks at all
of the connected Inputs and acts on the information from
certain number of the inputs that agree. This is commonly
known as a 'voting' system.
4- Output interface modules receive the outputs from
the proccessing unit and provide to the output circuits
(Relays)
5- The Interface relay provides electrical isolation
between the plant and fire &Gas control panel and provide
the output devices with the required power for operation.
6- The output devices are either alarms(
audible /optical) and/or control circuits.

Normally a protected plant is divided into fire areas and
each fire area has its own detection, alarm, control and
extinguishing system (if used).
If both fire and gas detection are required, these systems
share common control panels.
The fire detection and alarm system has manually operated
call points and automatic smoke, heat and flame detectors
located in areas where a fire hazard may exist.
Manual initiation of critical control actions overrides any
software-based system.
A brief description of the types of detectors and output
systems is given on the following pages.
The type of a Fir & Gas control panel and associated
detectors/outputs depends on the type of the controller it
self.

Addressable type system
If the controller is intelligent type, the detectors will
be addressable types, which are individually identified at
the F&GCP via a data highway. If the detector is not
addressable type then it is normally connected through a
dedicated interface module located near to the detector.
The addressable detectors and detector interface modules
respond to regular polls from the control panel and report
its type and status on the same loop (normal, alarm, open
circuit, short circuit...etc.).

Traditional type system
If the controller is traditional type (composed of discreet
electronic modules), the detectors are of the traditional
type, which changes the value of the electrical current in
its loop via normal wiring connections.
Each loop is identified on the F&GCP as a Zone.
The zone could include one or more of the traditional
detectors.
The activated detectors can not be individually identified
on the F&GCP, only they can be identified by observing the
integral LED on their locations.

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