Specification :

Model 451P
Pressurized ¦ÌR Ion Chamber Survey Meter

High sensitivity ¦ÌR measurements of exposure and exposure rate
Available with dose equivalent energy response (SI units)
Fast response to measure radiation from leakage, scatter beams and pinholes
Ergonomic, anti-fatigue handle with replaceable grip and wrist strap
Excel add-in for Windows ® for data logging and selection of instrument operating
parameters (optional)
Low noise chamber bias supply for fast background reading
Choice of bright, highly visible colors
Easy touch keys
INTRODUCTION
The Model 451P state-of-the-art ion chamber survey meter is a hand-held battery
operated unit designed for use in both rugged and normal environments. The
Model 451P features a pressurized ionization chamber, providing enhanced
sensitivity and improving energy response to measure gamma and X-ray radiation.
The Model 451P employs microprocessor and LCD technology. The ergonomic
handle, features a large diameter cushioned grip and is designed to reduce fatigue
associated with extended use. The case is constructed of lightweight, high strength
materials and is sealed against moisture. The user must specify R or Sv when
ordering.
The display features an analog bar graph, 2 1/2 digit digital readout, low battery
and freeze mode indicators. User controls consist of an ON/OFF button and a
MODE button. The unit is auto-zeroing and auto-ranging. The display features
circuitry that automatically activates the backlight in low ambient light conditions.
The RS-232 interface can be connected directly to a computer for use with the
Excel add-in for Windows ® , enhancing the functionality of the instrument. The
software allows for data retrieval, user parameter selection and provides a virtual
instrument display with audible (requires sound card) and visual alarm indication.
The software may be customized by the user for specific applications.

APPLICATIONS
The Model 451P is used in a wide range of medical and health physics applications.
The Model 451P was designed to measure leakage and scatter around diagnostic
X-ray and radiation therapy suites. Also, the Model 451P is ideal for site surveys
and is regularly used by X-ray manufacturers, government agencies, state
inspectors,
research labs, biomedical technicians, and in airports for baggage inspection
equipment maintenance.

FEATURES
" Ideal for a wide range of applications including NDT, X-ray, and environmental
" Battery operated
" Auto-ranging and auto-zeroing
" RS-232 communications interface
" Measures rate and dose simultaneously
" Tripod mount for stationary, area monitor applications
" Freeze mode indicates peak reading
" Programmable flashing display
" Automatic, ultra-bright LCD display
" Separate integrate mode
" Excel add-in for Windows ® (optional)
" Real-time data logging
" Downloading of 2700 data sets stored in instrument
" Virtual instrument display with audible and visual alarm indication
" Supports user instrument configuration and parameter selection
" User selectable modes

SPECIFICATIONS
Radiation Detected
Beta above 1 MeV
Gamma and X-rays above 25 keV
Operating Ranges
0-500 ¦ÌR/h or 0-5 ¦ÌSv/h
0-5 mR/h or 0-50 ¦ÌSv/h
0-50 mR/h or 0-500 ¦ÌSv/h
0-500 mR/h or 0-5 mSv/h
0-5 R/h or 0-50 mSv/h
Accuracy
Within 10% of reading between 10% and 100%
of full scale indication on any range, exclusive
of energy response. Calibration source is 137 Cs
Detector
Chamber: 300 cc volume pressurized air
ionization chamber to 6 atmospheres
Controls
ON/OFF and MODE
Automatic Features
Auto-zeroing, auto-ranging, and auto-backlight
Response Time
Analog response time from 10% to 90% of
reading for a full scale step increase is dependent
on operating range. Response time for a step
increase in radiation exposure rate from
background:
Step increase,
background to
Time to reach 90% of
final value (seconds)
400 ¦ÌR/h 4.8
4 mR/h 3.3
10 mR/h 4.3
40 mR/h 4.5
100 mR/h 2.7
1 R/h 2
4 R/h 2.7
The following table shows time measured from
10% to 90% of final value for a step increase or
decrease in exposure rate such that a range change
does not occur. These values are the response
times for the various ranges:
Range 10% - 90%
(seconds)
0-500 ¦ÌR/h (5 ¦ÌSv/h) 5
0-5 mR/h (50 ¦ÌSv/h) 2
0-50 mR/h (500 ¦ÌSv/h) 1.8
0-500 mR/h (5 mSv/h) 1.8
0-5 R/h (50 mSv/h) 1.8
Power Two 9-volt alkaline, 200 hours operation
Display LCD analog/digital with backlight
Analog100 element bar graph 2.5 in (6.4 cm) long. Bar
graph is divided into five major segments, each
labeled with the appropriate value for the range
of the instrument
Digital 2 1/2 digit display is followed by a significant
zero digit depending on the operating range of
the instrument. The units of measurement are
indicated on the display at all times. Digits are
1/4 in (6.4 mm) high. Low battery and freeze
indicators are also provided on the display
Warm-Up Time
Less than two minutes for initial operation when
the instrument is in equilibrium with ambient
temperature
Environmental
Temperature Range - 20¡ãC to + 50¡ãC
Relative Humidity 0 to 100%
Geotropism Negligible
Typical Energy Dependence
16 Nitrogen gamma rays are 110% to 120% of
indicated readings as determined at the University
of Lowell

Dimensions 4 in (w) x 8 in (d) x 6 in (h) (10 x 20 x 15 cm)
Weight 2 lb 6 oz (1.07 kg)
451P Models
Model 451P-RYR 451P w/standard chamber
Model 451P-YGG 451P w/standard chamber
Model 451P-DE-SI-RYR 451P w/Dose
Equivalent chamber
Model 451P-DE-SI-YGG 451P w/Dose
Equivalent chamber
Suffix designation RYR = Red/yellow/red
Suffix designation YGG = Yellow/gray/gray
Options Model 451EXL Excel add-in for Windows ®
and RS-232 interface cable
Model 190HPS Single Unit Carrying Case
Model 190HPC Multiple Unit Carrying Case
Model 62-103 137 Cs 10 ¦ÌCi Check Source
Modes 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
Freeze mode will place a tick mark on the bar
graph display to hold on the peak displayed value.
The unit will continue to read and display current
radiation values
Model 451P Typical Energy Dependence
Indicated/ Actual
Effective (keV)
Specifications are subject to change without notice.
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