16
The Set Cal Constant Screen
Figure 4(6)
The Calibration Constant is a conversion factor used to convert
the detector’s count rate into units of exposure or dose rate.
From the calibration Settings screen, tap the “Cal Constant…”
button to open the Set Cal Constant screen.
Use the keypad to enter the desired Cal Constant. Any value,
including fractional, may be entered. The modified Cal Constant
setting will not be applied until the “Set” button is tapped, at
which point the display will return to the Calibration Settings
screen. Tap the “Back…” button instead to cancel any modified value and return to the Calibration
Settings screen.
The Cal Constant is usually determined by exposing the detector to a known radiation field (in units of mR/h)
of about 10 to 20% of the maximum value the detector is capable of detecting, noting the count rate in cps,
and dividing cps by mR/h.
The Set Calibration Date Screen
Figure 4(7)
The Calibration Date is used to set the Cal Date displayed in the
System screen. From the calibration Settings screen, tap the “Cal
Date…” button to open the Set Calibration Date screen.
Use the keypad to enter the Calibration Date. Any value may be
entered and no checking is performed regarding format. The
modified Calibration Date will not be applied until the “Set”
button is tapped, at which point the display will return to the
Calibration Settings screen. Tap the “Back…” button instead to
cancel any modified value and return to the Calibration Settings
screen.
Setup and Calibration Sequence
1.
Disable alarms by setting all three alarm levels to zero.
2.
Set threshold and high voltage to appropriate values, generally with the Base Unit set to cpm or cps.
3.
Determine and set the Dead Time for the detector in use.
4.
Determine and set the Calibration Constant for the detector in use.
5.
Set the Base Unit to the desired minimum unit of measure.
6.
Confirm calibration by challenging with known levels of radiation and observing the indication.
7.
Set Alarm Levels, Alarm Indicators, and Communication Settings as desired.
8.
Set the Calibration Date.
Figure 4(6)
Figure 4(7)