4 (w) x 8 (d) x 6 in (h) (10 x 20 x 15 cm)

2.5 lb (1.11 kg)

Alpha above 7.5 MeV, Beta above 100 keV, and Gamma above 7 keV

• 0 to 5 mR/h or 0 to 50 µSv/h
• 0 to 50 mR/h or 0 to 500 µSv/h
• 0 to 500 mR/h or 0 to 5 mSv/h
• 0 to 5 R/h or 0 to 50 mSv/h
• 0 to 50 R/h or 0 to 500 mSv/h

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

349 cc volume air ionization

246 mg/cm² thick phenolic

6.6 mg/cm² Mylar, protected by steel mesh, 46 cm² detection area

440 mg/cm²

In order to achieve energy response consistent with measurements of H*(10) as required by ICR4-47, aluminum has been added to the back wall, 38% of the side wall area, and to the beta slide. With the Beta Shield open, the 451B can measure skin dose at 10* (0.07), and Deep Dose H* (10) with Beta shield closed.

ON/OFF and MODE

Auto-zeroing, auto-ranging, and auto-back

• 0 to 5 mR/h (0 to 50 µSv/h) 8 sec
• 0 to 50 mR/h (0 to 500 µSv/h) 3 sec
• 0 to 500 mR/h (0 to 5 mSv/h) 2 sec
• 0 to 5 R/h (0 to 50 mSv/h) 2 sec
• 0 to 50 R/h (0 to 500 mSv/h) 2 sec

Two 9 V alkaline, 200 hours operation

One minute

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

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

100 element bar graph 6.4 cm long. Bar graph is divided into 5 major segments, each labeled with the appropriate value for the range of the instrument

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 in (6.4 mm) high. Low battery and freeze indicators are also provided on the display

- 4º to + 158º F (- 20° to + 70° C)

0 to 100%  (@140° F or + 60° C)

Less than 1%