READIT-2007 - Indira Gandhi Centre for Atomic Research

detectors are suitable for detecting fire in the place where materials stored generate
smoke just before the out break of fire.
Beam Detectors: A Beam Detector consists of a transmitter and receiver and operates
in line of sight. The system has a separate alarm and trouble signals which distinguish
between a percentage of signal blockage and a total beam block. Beam Detector is
uniquely suitable for protecting open areas with high ceilings where conventional spot
type smoke detectors are difficult to install and maintain. Typically, this type of
Detectors is suitable for Auditorium, Garage or Warehouse.
Other Devices:
1. Manual Call Point: Manual Call Point is a device meant for human beings
to operate in the event of visual fire or smoke where the sensors failed or
delayed to operate. MCP is also interfaced with the main fire alarm system.
Typically these devices are installed near the exit door / corridor / staircase.
2. Isolator: An Isolator Device will detect short-circuit and isolates the shortcircuited
segment from a loop. When the faulty sensor(s) removed or
replaced the isolator will return to normal operation.
3. Response Indicator: Response Indicator is a Light Emitting Diode (LED),
which indicates the status of the corresponding sensor. Normally these
indicators are fitted outside the closed rooms, so that the person can ascertain
the status in the event of alarm condition. This reduces the time consumption
while searching for the doubtful location.
4. Hooter or Sounder: Hooter or Sounder is a device powered by the loop
supply and does not require any separate power to activate. If the volume is
insufficient separate power unit can be attached. Generally the device is
designed such that the current consumption is low with high volume and no
additional power supply is required.
4. GENERAL GUIDELINES
1. Factors involved in Selection of an Ideal System:
a. Assessment: Assessment has to be made with respect to the area to be
covered, layout of the building, types of material housed. In this aspect,
engagement of a professional in the field especially from the Industry is most
advisable so that the exact quantity and type of detectors can be technically
assessed.
b. Fire Alarm Panel: Selection factors like number of Detectors and Devices
should be taken into consideration. Each loop card should support addressable
devices (Detector, Isolator, Hooter, Indicators). Normally, an ideal panel
should be capable of having 99 Detectors and 99 Devices per loop. The panel
should be able to accommodate enough number of loops to cover the building
and the future expansion. Hence there shall be provision for sufficient number
of loops.
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