Fluke Biomedical 451P - Manual (Page 11)

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Introduction
The Model 451P Ion Chamber Survey Meter (the Survey Meter) is a hand-held,
pressurized, battery operated meter designed to measure gamma and x-ray
radiation above 25 keV, and beta radiation above 1 MeV, using the latest CMOS
and LCD technology. The Survey Meter case is constructed of high strength ABS
plastic. A gasket seals moisture out of the Survey Meter and provides a cushion
for the internal components. The readout consists of a 2½ digit liquid crystal
display and a 100 segment analog bar graph. The bar graph contains a zero
segment and twenty groups of five segments each. A permanent scale is located
on the display screen. The major divisions of the scale indicate the units
corresponding to the range that the meter is measuring. The units of
measurement show next to the 2½ digit display. LOW BAT and FREEZE appear
on the display when the Survey Meter is operating in these modes. External
controls consist of an ON/OFF button and a MODE button. The Survey Meter is
auto-ranging and auto-zeroing. The auto-on circuit for the backlight is enabled
when twilight conditions occur. An internal factory-set alarm blinks the display if
the rate exceeds 5 R/hr. Two 9 volt batteries, located in the rear of the Survey
Meter, provide over 200 hours of continuous operation.
Intended Use
The 451P Ion Chamber Survey Meter is a hand-held, pressurized, battery
operated unit designed to measure gamma and x-ray radiation above 25 keV and
beta radiation above 1 MeV.