VENTILLATION DUCT RADIATION MONITOR type GA721 manufactured by NUCLEONIX SYSTEMS employs state-of-art micro-controller based design and is primarily meant to serve as a Ventilation Duct Radiation Monitor to indicate dose rates and give alarm, visual and aural, once the dose rates exceed the preset level fixed by the user. Also relays will be activated on alarm.

This unit will be useful for monitoring gross gamma activity in the exhaust air duct of Reactor building/Service building Ventilation System and to give activity level signal output to Local as well as control room. The unit consists of (a) Detector assembly and (b) monitor unit. The Detector assembly will be in a Lead Castle close to duct and away from the monitor unit and is connected by means of a signal / EHT cable of about 10 meter length.

This unit indicates the dose rate digitally on a 4 x 7 segment LED display. Unit has additionally 16x2 LCD dot-matrix display which indicates fault dignostic info & preset level & other configuration parameters. Each of the annunciator windows for NORMAL and ACTIVE conditions has LED array. Once alarm triggers ACTIVE window starts blinking.
Unit can be programmed / configured using front panel keypad which can be deactivated after completion of programming. Configuring the unit namely setting preset level, setting reset mode - AUTO/MANUAL etc are achieved by this keypad.
Unit also performs self-diagnostics for EHT failure, pulse processing electronics failure & detectors failure on power up.
Alarm acknowledge and reset pins are provided on the circular I/O connector for remote acknowledge & reset. RS485 port is also available optionally.