DECTEOR : GM tube LND 719 or its equivalent
CHANNELS : 12 channels in all, covering entire body from head to foot on each side of the person using a total of 54 detectors.
SHIELDING : Suitable lead shielding for all the channels to minimize background radiation.
BACKGROUND : System periodically checks for detector background & updates it, which is stored in the EEPROMs. Background Counts are automatically subtracted while contamination of personnel is monitored.
During background check, if high background or low background is sensed, instrument will halt ready status and show appropriate messages and continue to update background till recovery.
PERSON SENSING : A person standing inside the portal is automatically sensed by IR source detector combination.
COUNTING SEQENCE: Once a person stands inside the portal monitor and activates the IR optical sensors the counting sequence is initiated and ‘COUNTING ON’ LED is activated.
Counting with automatic background subtraction goes on for 5 sec (or for the preset time set by Health Physicist) and contamination status is reported visually.
AUDIO/VISUAL INDICATIONS & ALARMS: Refer to table 1.
DISPLAY : 7.5” TFT colour display for showing user friendly messages, for guidance during monitoring and for mimic indications.
KEYPAD : A detachable keypad has been provided for the health physicist to be able to set and configure the Portal Monitor.
MIMIC: A human picture which indicates region of contamination has been provided on the TFT monitor
USER GUIDANCE: Suitable user guidance audio / visual messages are generated during monitoring
ALARM LEVELS : Each counter channel can count up to 9999 counts. So alarm level can be set for each channel between 0-9999 counts. Other units selectable are CPS & CPM
SYSTEM SETTINGS : Background counting : 1-99 seconds, Personal monitoring time counting time : 1 - 99 seconds, Alarm range : 0-9999 CPS/CPM/Counts, Background low limit : 0-9999 CPS/CPM/ Counts, Background high limit : 0-9999 CPS/CPM/Counts.
BYPASS FAULTY : All detector signals are independently counted. This allows any faulty GM detector channel to be bypassed and system usage can be resumed. |
SELF DIAGNOSTICS : It performs diagnostic check at power-up and also on user prompt to check for various parameters of the instrument. Self check can be done by the user using hand-held keypad. The various checks that are performed are EHT check, detector check, Pulse processing electronics check for faulty channel identification and high background check.
RELAY CONTACTS : Alarm Change Over Contacts – 2 sets for clean condition for turnstile operation.
TEST FACILITIES : Provision for performing test background, test acquire directly through keypad.
DATA STORAGE : Automatic storage of alarm data along with time stamp for upto 50 readings.
ETHERNET SPECIFICATION :
Type : Ethernet Communication port
Protocol : MODBUS TCP
Bit Rate : 10 Mbps
Connector : RJ 45
HV REDUCTION : HV to the tubes is reduced to 0V, when not in use to extend life of the GM tubes.
DETECTOR ARRANGEMENT : All Detectors are assembled on SS trays which can easily slide out from the monitor for maintenance purpose.
All GM tubes are clamped and mounted on sockets for easy removal during maintenance. Each detector has individual preamplifier with individual counting signals for all detectors.
DECTOR EFFICIENCY :
a. Overall efficiency for 4 detector arrangement of chest area = 4%
b. Overall efficiency for 3 detector arrangement of leg area = 3.5%
c. Overall efficiency for 2 detector arrangement for head & feet = 5%
FRONG, BACK& TOP DECTOR ASSEMBLIES : Lead shielding of 6 mm will be used. The detectors will be covered with a well finished SS sheet grill. The top grill assembly will be moveable up/down manually and will retain desired position once adjusted. Height will be easily adjustable to suit height of every person.
FOOT DECTORr ASSEMBLY : Two detachable SS trays with detector assemblies mounted on them are used for left and right foot. Both the assemblies are covered with SS grill. Detectors are shielded with a 1” thick lead. Detector assemblies have easy lift and remove arrangement. An additional SS cover is also provided for entire foot assembly to hold plastic sheet to prevent contamination.
POWER SUPPLY : 240V +/- 10%
OPERATING ENVIRONMENT : Upto 50oC, RH 95%, continuous operation.
PORTAL DIMENSIONS : Side Entry SS frame of below dimensions
Inner (approx) 6’ 6” X 1’ 10” X 3’ 4”
Outer(approx) 7’ X 3’ X 3’ 4”
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