Model 450B Ion Chamber
Survey Meter
·
Auto
ranging, auto zeroing
·
Light
weight, easy to use
·
Freeze/Integrate
functions
·
Display
flash alarm set point
·
Rugged,
moisture proof
·
Available
in SI units
Description
The Model 450B is an innovative radiation
survey instrument. It is based on the proven characteristics of the ion chamber
radiation detector married to the latest CMOS microprocessor technology and
liquid crystal displays.
The only controls present on the basic
instrument are an ON/OFF button and a MODE button. No other controls are
necessary because the instrument is both auto-ranging and auto-zeroing.
The display is unique, offering both a 100
element analog bargraph that is fully labelled with scale digits and a 2 1/2
digit digital display that also provides the proper units of measurement. The
bar graph is provided with a faster time constant than the digital display
making the instrument ideal for surveys.
The top surface of the instrument has an
overlay which covers both of the display switches, completely sealing this
surface. The instrument is fully gasketed to make it moisture proof. The gasket
also serves to shock-mount the printed circuit boards, liquid crystal display,
and ion chamber assembly. The instrument will remain operational after a drop
from a height of 3 ft. onto a concrete floor.
The variables FREEZE, INTEGRATE: R or Sv are
factory set when the Model 450B is purchased without a communicator. The
customer can choose settings.
The FREEZE button is a special feature that
permits the instrument to remember and indicate the highest dose rate from the
time the instrument is placed in the freeze mode, This feature permits placing
an instrument in a potentially high radiation area and determining the maximum
value the instrument sees.
The Integrate Mode operates continuously 30
seconds after the instrument has been turned on. Integration is performed even
if the instrument is displaying in mR/h or R/h.
Calibration is accomplished by an infra-red
two-way communication, Model 450-1A. The communicator uses a RS-232 port. The
two-way communicator can be used to interrogate the instrument for calibration
information, perform a calibration of the instrument, change between the
integrate display mode or the FREEZE display mode, or change units
(English-Si).
The IR Communicator also allows the use of the
Model 450B as a remote detector.
To guard against battery-related instrument
failure, a "Low Battery" condition is indicated continuously on the
face of the display when a battery change is required. A 400 mg/cm2 thick
bakelite slide is provided to protect the Mylar window and serve as an
equilibrium shield. The bakelite slide is positioned to the lower part of the
case when using the mylar window.
