• 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 Windows-based Excel add-in for data logging

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 (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.

Specifications
Radiation Detected:
  Beta above 1 MeV
  Gamma and X-Rays above 25 keV

Operating Ranges - Response Time:
  0 to 500 µR/h - 5 seconds
  0 to 5 mR/h - 2 seconds
  0 to 50 mR/h - 1.8 seconds
  0 to 500 mR/h - 1.8 seconds
  0 to 5 R/h - 1.8 seconds
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
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" (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" (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 .
Temperature Range: -4° to +122°F (-20° to +50°C)
Relative Humidity: 0 to 100%
Geotropism: Negligible
Size: 4" W x 8" D x 6" H (10 x 20 x 15 cm)
Weight:  2.4 lb (1.07 kg)

Tested. Meets applicable standards.

If you need to return this unit, please contact RPDinc to obtain an RMA number and follow these instructions:
Re-Calibration - Return Shipping Instructions