Fluke Biomedical 451P - Manual (Page 15)

Ion Chamber Survey Meter
Features
5
Features
The following sections describe the features of the Survey Meter.
Overrange Rate
If the instantaneous radiation rate measured by the Survey Meter exceeds 5 R/h,
the 'R' in 'mR/h' or the 'Sv' in 'Sv/h' displayed will blink to notify the user that a
potential error in the integrated radiation value exists. The blinking will stop when
the integrated value is cleared. This, however, may also clear the log data RAM.
Low Battery Indicator
There are about 6 hours of operation remaining when the LOW BATTERY
indicator first becomes visible. When the LOW BATTERY indicator blinks, there
is less than 1 hour of operation remaining. These times are for two batteries
installed and from the first occurrences of these indications. If the Survey Meter
is turned off during a low battery condition, the batteries will recover somewhat,
but time of operation remaining will be less. The LCD low battery indicator is
disabled during communication mode. Be sure to use fresh batteries when
calibrating the Survey Meter.
 Warning
For safe operation and maintenance of the product, note the
chamber bias from the self-test. If chamber bias is LO, the
Product cannot measure high radiation rates accurately. The
Product requires service, contact Fluke.
Verify the chamber bias is low. Turn off the Survey Meter and replace with new
9 volt batteries. Turn on the Survey Meter. After the self-test, if blinking low
battery reoccurs, the bias is low.
Warm-up Time
The pressured ion chamber collection potential is 105 Vdc and is derived from
the 5 lithium cells. The warm-up time for a Survey Meter that has been off
12 hours or more is about 4 minutes for readings less than 20 ° R/h in a 10 μ R/h
or less background.