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451B Ion Chamber Survey Meter, with Beta Slide, Standard Chamber (R)

451B Ion Chamber Survey Meter, with Beta Slide, Standard Chamber (R)

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451B Ion Chamber Survey Meter, with Beta Slide, Standard Chamber (R).


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451B Ion Chamber Survey Meter, with Beta Slide, Standard Chamber (R).

The auto-ranging 451B measures radiation rate and accumulated dose from beta, gamma and x-ray radiation sources. The 451B’s site surveying capabilities make it well-suited for a wide range of end users, including: police and fire departments, x-ray manufacturers, government agencies, state inspectors, emergency response and HAZMAT teams, nuclear medicine labs, hospital radiation safety officers, and nuclear power workers. The ion chamber detector allows for a fast response time to radiation from leakage, scatter beams and pinholes. Additionally, the low noise chamber bias supply provides for fast background settling time. A sliding beta shield serves as an equilibrium thickness for photon measurements and enables beta discrimination. The digital display features an analog bar graph, 2.5 digit digital readout, low battery and freeze (“peak hold”) mode indicators, and an automatic backlight function. User controls consist of an ON/OFF button and a MODE button. The case is constructed of lightweight, high strength materials and is sealed against moisture. The RS-232 interface can be connected directly to a computer for use with the Excel add-in for Windows (Item 343-460), enhancing the functionality of the instrument. This software allows for data retrieval, user parameter selection and provides a virtual instrument display with audible (requires sound card) and visual alarm indication.

• High sensitivity measurement of rate and dose simultaneously, with the capability to record peak rate

• Auto-ranging and auto-zeroing

• RS-232 communications interface with optional Windows-based Excel add-in for data logging

• Ergonomic, anti-fatigue handle with replaceable grip, wrist strap and tripod mount

• Programmable flashing LCD display and audible alarm

• Easily-accessible battery door (operated by two 9-volt alkaline batteries) on the outside of the bottom case

Radiation Detected:
Alpha above 7.5 MeV
Beta above 100 keV
Gamma above 7 keV

Operating Ranges - Response Time:
0 to 5 mR/h - 8 sec.
0 to 50 mR/h - 2.5 sec.
0 to 500 mR/h - 2 sec.
0 to 5 R/h - 2 sec.
0 to 50 R/h - 2 sec.

Accuracy:  Within 10% of reading between 10% and 100% of full scale indication on any range, exclusive of energy response. Calibration source is 137Cs

Chamber:  349 cc volume air ionization
Chamber Wall:  246 mg/cm2 thick phenolic
Chamber Window:  6.6 mg/cm2 Mylar, protected by steel mesh, 46 cm2 detection area
Beta Slide:  440 mg/cm2

Controls:  ON/OFF and MODE
Automatic Features:  Auto-zeroing, auto-ranging, and auto-backlight
Power requirements:  Two 9 V alkaline, 200 hours operation
Warm-up time:  One minute

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

Display:  LCD analog/digital with backlight
Analog:  100 element bar graph 2.5" (6.4 cm) long. Bar graph is divided into 5 major segments, each labeled with the appropriate value for the range of the instrument

Digital:  2.5 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 0.25" (6.4 mm) high.  Low battery and freeze indicators are also provided on the display

Temperature Range:  -4° to +158°F (-20° to +70°C)
Relative Humidity:  0 to 100%, @ +60°C
Geotropism:  Less than 1%
Size:  4" W x 8" D x 6" H (10 x 20 x 15 cm)
Weight:  2.5 lb (1.11 kg)

Data Sheet


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