451P Pressurized μR Ion Chamber Survey Meter

The auto-ranging 451P ion chamber radiation survey meter features a pressurized ionization chamber, providing enhanced sensitivity (µR resolution) and improved energy response to measure radiation rate and dose from x-ray and gamma sources.

Categories: Radiation Safety, Raysafe

The auto-ranging 451P features a pressurized ion chamber, providing enhanced sensitivity (µR resolution) and improved energy response to measure radiation rate and dose from x-ray and gamma sources. Originally designed to measure leakage and scatter around diagnostic x-ray and radiation therapy suites, the 451P’s site surveying capabilities make it well-suited for a wide range of end users, including: x-ray manufacturers, government agencies, state inspectors, biomedical technicians, and maintenance technicians for airport baggage scanners.

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.

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.

Read the 451P Pressurized μR Ion Chamber Survey Meter Data Sheet

Features

Key Features

High sensitivity µR 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)

Tested. Meets applicable standards

Specifications

Product Specifications

Radiation detected

Beta above 1 MeV, Gamma and x-rays above 25 keV

Operating ranges

0 to 500 µR/h or 0 to 5 µSv/h
0 to 5 mR/h or 0 to 50 µSv/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 µR/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 µR/h (5 µSv/h) & 5 sec
	0 to 5 mR/h (50 µSv/h) & 2 sec
	0 to 50 mR/h (500 µSv/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	– 4º to 122ºF (- 20° to 50°C)
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)

Models and Accessories

Model Name	Description	Price List
451P-RYR	Pressurized µR Ion Chamber Survey Meter with standard chamber
451P-DE-SI-RYR	Pressurized µR Ion Chamber Survey Meter with dose equivalent chamber