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Model 52-1, 52-5 & 52-6 Series


  • Portable
  • 61 cm (24 in.) or 81.3 cm (32 in.) Wide Opening
  • Plastic Scintillator Detectors
  • Built-in Person Counter
  • Background Updating and Subtraction
  • Sets Up In Minutes
  • Easy to Operate
  • Wheeled Transport Case Included
  • Meets FEMA-REP-21
  • Includes Sleeve for Weather Protection

The Model 52-1, 52-5, and 52-6 Series Portal Monitors are used for beta-gamma personnel contamination monitoring and meet the FEMA standard for Emergency Response Portal Monitoring (FEMA-REP-21). They are designed to be disassembled for ease of transportation and storage and can be set up in five minutes or less without any tools.

The non-volatile parameters are preset at the factory to detect a 1.0 μCi 137Cs source in a 10 μR/hr background field. The electronics are microprocessor-based for ease of setup and reliability. Status LEDs indicate count-cycle status. Audible signals accompany the LEDs for additional indication. Detector counts, background, and all parameters may be viewed on the Liquid Crystal Display (LCD). All setup is accomplished by way of pushbuttons located below the LCD.

These portal monitors can be operated in a walk-through basis with a quick scan occurring while a person is positioned within the portal. In this mode, checking is performed every 200 milliseconds while the portal is occupied, and 600 milliseconds before and 600 milliseconds after the portal is occupied. The portal monitor can also monitor in a stop-and-count mode, allowing for a more sensitive scan. In stop-and-count mode, the fixed count time may be set from 1 to 20 seconds.

These instruments have automatic background update and dynamic alarm setting capabilities. On startup, the instrument will take a background count and calculate alarm levels for each detector. Self-diagnostic routines check the background count and warn if the background becomes either too high or too low.

Alarms are calculated with a user-adjustable sigma parameter and the current background count. During setup, the user can also specify individual alarms only, sum alarm only, or both individual and sum alarm. The sum alarm groups upper detectors and lower detectors.

A polypropylene weather sleeve is included to protect against wet weather conditions. These instruments are able to operate from 85 to 250 Vac 50/60Hz without a voltage selector switch. They may also be powered from the supplied vehicle cigarette lighter adapter, or three or six “D” cell batteries.

Vehicle Monitoring

The Model 52-1, 52-5, and 52-6 Series can also be used as vehicle monitors using the optional vehicle conversion kit. See the Options tab for more information.

Water-Resistant Versions

Ludlum also offers some water-resistant versions: Model 52-1W (P/N 48-4300), Model 52-1-1W (P/N 48-3516) and Model 52-6-1W (P/N 48-4312). See the data sheets on the documents tab for more information. (Note: The water-resistant versions can only be used for gamma contamination monitoring.)

Download Datasheets

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