Technical Data

Gamma Zone monitor type GA 720N, designed & manufactured by NUCLEONIX SYSTEMS is primarily meant to serve as a Gamma Zone Monitor to indicate dose rates and alarm status (visual and aural), once the dose rates exceed the preset level fixed by the user. Also relays will be activated on alarm condition. Unit also indicates fault diagnostic conditions on 1/2” LED display.

Unit is provided always with an external detector probe mounted on the top of Gamma Zone monitor enclosure by a clamp, with a short cable of 1 meter length by default. Longer cable lengths can be provided on request.This unit will be useful for monitoring Gamma dose rate levels in working areas of radioisotope laboratories, in oncology departments near cobalt therapy machines or Brachytherapy machines or at other similar medical systems & also in a medical cyclotron facility, or at other medical & industrial radiological installations.This unit indicates the dose rate digitally on a 6 x 7 segment LED display.

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 HV failure, pulse processing electronics failure and detectors failure on power up

Features

• Uses SoC, based on ARM Cortex A5 400MHz ,1.5MB SRAM,128MB Flash,extensive use of peripheral devices & Ethernet interface has been employed.
• Uses Microcontroller for counting radiation pulses, fault diagnostics, setting HV etc.
• Dose rate, range covered is (0.01 – 100) mR/hr by default, with option of selection of other three ‘units’ namely µSv/hr, CPS & CPM.
• Auto ranging & auto TC selection in the range of 30 sec to 0.5 sec depending upon detector count rate.
• 5” TFT display indication for dose rate, alarm status & configuration settings.
• Designed using GM tube type LND 713 or its equivalent.
• Large size WINDOW indication on TFT display for NORMAL & ACTIVE alarm condition.
• Alarm set point & ACK / RST through touchscreen.

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Specifications

Radiation to be detected :	Gamma Radiation & X- Rays.
Range :	0.01 -100 mR/hr 0.1 – 1mSv/hr 0- 50000 CPM Range and Unit are configurable.
Detector :	Energy compensated Halogen -quenched G. M. Tube LND713 or equivalent having a sensitivity of 7.5 cps / mR/ hr .
Energy Response :	+/-25% from 100keV upto 1.25MeV.
Accuracy :	+/ – 10% Full scale with Cesium source.
EHT :	400V to 700V DC adjustable (Typical 500V) (factory set).
Display :	5”TFT is used for display of doserate, hardware status information & also for visualization of preset alarm and other parameters.
Overload :	Senses overload above 200% of full scale and upto 1 R/ h & indicates on display “OFL”.
Over-range :	Senses if the radiation field being measured has exceeded the measurement range of the instrument and upto 200% of the instrument and displays “OVR”.
Time Constant :	First Stable reading on Power ON within 1 min. Normal (Slow) : 30 sec to 0.5 sec automatically varying inversely with the radiation level.
Abrupt detection :	Update the current reading within 2 sec.
Calibration Accuracy :	+/- 10% through out the range.
Alarm range :	0.01 mR/Hr to 99.99 mR/hr. 0.1 µSv/Hr to 999 µSv/hr. 1-50000 CPM . The alarm level setting will be carried out through Radgrid Software by Ethernet Communication.
Alarm Indication :	a) Red Mimic flashing large area on TFT display. b) Loud alternating audio tone (Dual frequency tone).

Alarm annunciation scheme

As tabulated below :

Instrument Controls :

a) Acknowledgement icon for muting audio alarm.

b) Reset icon for resetting the Alarm indication and alarm relay.

Instrument Fault indication :

HV failure : Visual alarm with flashing red MIMIC indication & “HV” message on display.

Detector failure :

Visual alarm with flashing red MIMIC & “Detector Failure” message on display. Fault indications shall be cleared automatically if normal status is resumed.

Detector Housing:

(In case of External Probe)

a. The Smart Probe is located external to the Display Unit.

b. It is housed in a suitable, air-tight SS shell with built-in pre-amplifier, HV & Microcontroller with RS485 interface.

c. The instrument is provided with 10 mtr cable between Smart Probe and the monitor.

d. The detector housing qualifies industrial protection Class IP-54.

e. A separate mounting bracket for detector housing is provided.

External Console

RJ 45 connector for Ethernet port.

Computer Interface : The monitor (NXG_AGM2 or AGM3 only) has a Ethernet 10/100Mbps port for interfacing with a remote Windows PC. The features supported by Ethernet port are given below.

The PC and the NXG_AGM unit shall operate in a Client/ Server configuration and the software(RADGRID) protocol will be TCP.

The PC software shall give commands and send queries. The NXG_AGM unit will carry out various functions in response to the queries.

The firmware of the monitor shall be able to send the instrument data like instrument IP, instrument type, input range, display range, alarm settings, alarm status, current reading, diagnostic status of EHT/GM tube etc. to the Host PC on demand.

The firmware shall be able to receive commands from Host PC and carry out the setting of different parameters like instrument IP, instrument type, input range, display range, alarm settings, Ack, Reset, instrument address etc.

It can store data for every second. Last 60 Days data will be in store in the Instrument.

Input Power : 230V AC +/-10%.
Mechanical Enclosure:
Size: 180H x 178W x 38D.
Weight: 1Kg approx.