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  • Ludlum Model 52-1 Portable Portal Monitor

$15,000.00 $7,500.00


  • Portable
  • 61 cm (24 in.) or 81 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

4 in stock

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The Model 52-1 Portable Portal Monitors are used for beta-gamma contamination monitoring on personnel 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.

Each instrument’s non-volatile parameters are preset at the factory to detect a 1.0 μCi 137Cs source in a 10 μR/hr background field. Microprocessor-based electronics provide ease of setup and reliability. Status LEDs indicate count-cycle status and audible signals accompany the LEDs for additional indication. Detector counts, background, and all parameters may be viewed on the instrument display. All setup is accomplished by way of pushbuttons located below the display.

These portal monitors can be operated in a walk-through mode 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.

Included with each instrument are a wheeled transport case and a clear polypropylene sleeve to protect against wet weather conditions.

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

Model Part Number Detectors Outside Dimensions
(H x W x L)
Inside Dimensions
(H x W)
Total Detector Volume Weight
52-1 48-3172 4 side 211 x 81.3 x 45 cm
(83 x 32 x 17.5 in.)
206 x 61 cm
(81 x 24 in.)
11 L
(672 in3)
Approx. 32 kg (70 lb),
45 kg (100 lb) in case

Additional information

Weight 100 lbs
Dimensions 84 × 30 × 12 in