Fluke Biomedical 451P - Manual (Page 21)

Ion Chamber Survey Meter
Operation
11
MODE Button
To configure the MODE button to the opposite function without a RS-232
connection, use the following procedure:
1. Turn off the Survey Meter.
2. Press the MODE button.
3. Turn on the Survey Meter while continuing to press the MODE button.
4. Release the MODE button when the display is in the “all elements on”
condition.
5. Use the MODE button to toggle the Survey Meter between the Rate mode
and the newly selected Freeze or Integrate mode.
Freeze Mode
When configured to select the Freeze mode, the MODE button acts as a toggle
switch. Press the button until FREEZE appears on the display. Operation in the
Freeze mode gives the user a constant reference of the highest exposure rate
obtained from the time the freeze function is initialized. The highest reading
appears as a single bar on the bar graph. The current reading continues to
display on the digital display and the bar graph. If a measurement is obtained
which exceeds the freeze bar reading, the freeze bar moves to the higher
measurement point. The operating range of the Survey Meter remains locked on
the highest range attained during the Freeze mode so that the scale and the
multiplier remain the same.
For example, assume the scale units appear as 10, 20, 30, 40, 50, and the
freeze bar is at 47 mR/h on the bar graph. If the Survey Meter then measures a
radiation field of 120 mR/h, the scale units will change to 100, 200, 300, 400, 500
and the freeze bar appears on the graph at 120 mR/h. If the Survey Meter
measurement goes below 100 mR/h, the units on the scale will not change until
the Survey Meter is taken out of the Freeze mode. However, the digital display
continues to show the current reading. The Survey Meter operates in the Freeze
mode until the user toggles the MODE button to return to the normal operating
mode.
Integrate Mode
The Integrate mode is operational 30 seconds after the Survey Meter is turned
on and all of the time after that. However, the integrated exposure displays only
when the MODE button has been configured as a toggle to display exposure
rate/integrated exposure. If the MODE button is pressed within the 30 second
initialization period of the Survey Meter, the display will read “0”.
When integration starts, “0.0
μ R” displays. Toggle MODE to read exposure rate
as required.
To reset the integration display, toggle the display from the Rate mode to the
Integrate mode. Keep the MODE button pressed for approximately 5 seconds.
The display will clear, and then read “0.0 μ R.” Exposures are accumulated up to
99 R.