Fluke 451P Survey Meter

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 (451EXL), 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.

Key Features:
High sensitivity µ R measurements of rate and dose simultaneously, with the capability to record peak rate
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
RS-232 communications interface with optional Windowsbased Excel add-in for data logging
Available with dose equivalent energy response (SI units)

Product Specifications
Radiation detected Beta above 1 MeV, Gamma and X-rays above 25 keV
Operating ranges 0 to 500 µ R/h or 0 to 5 µ Sv/h
0 to 5 mR/h or 0 to 50 µ Sv/h
0 to 50 mR/h or 0 to 500 mSv/h
0 to 500 mR/h or 0 to 5 mSv/h
0 to 5 R/h or 0 to 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 137CS
Detector Chamber: 230 CC volume pressurized air ionization chamber to 8 atmospheres or 125 psi
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 to increase, background to & Time to reach 90% of final value: 400 µ R/h & 4.8 sec
4 mR/h & 3.3 sec
10 mR/h & 4.3 sec
40 mR/h & 4.5 sec
100 mR/h & 2.7 sec
1 R/h & 2 sec
4 R/h & 2.7 sec

The following 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% to 90%: 0 to 500 µ R/h (5 µ Sv/h) & 5 sec
0 to 5 mR/h (50 µ Sv/h) & 2 sec
0 to 50 mR/h (500 µ Sv/h) & 1.8 sec
0 to 500 mR/h (5 mSv/h) & 1.8 sec
0 to 5 R/h (50 mSv/h) & 1.8 sec

Power requirements Two 9 V alkaline, 200 hours operation
Warm-up time Less than two minutes for initial operation when the instrument is in equilibrium with ambient temperature
Display LCD analog/digital with backlight Analog
100 element bar graph 2.5 inch (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
2.5 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 inches (6.4 mm) high. Low battery and freeze indicators are also provided on the display
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

Environmental Temperature range - 20 C to 50C)
Relative humidity 0 to 100%
Geotropism Negligible

Dimensions 4 (w) X 8 (d) X 6 in (h) (10 X 20 X 15 cm)
Weight 2.4 lb (1.07 kg)