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  • Ludlum Model 52 Portable Portal Monitor

$19,000.00 $9,500.00


  • Portable
  • 81.3 cm (32 in.) Wide Opening
  • Uses 18 GM 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

25 in stock

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The Model 52 Portal Monitor is used for Beta-Gamma personnel contamination monitoring and meets the FEMA standard for Emergency Response Portal Monitoring (FEMA-REP-21). It is designed to be assembled in five minutes or less without tools, and can be quickly disassembled for ease of transportation and storage. All parameters are stored in non-volatile memory, which requires no battery backup. These parameters allow easy operation with minimal setup by minimally trained personnel. The parameters are preset at the factory to detect a 1 µCi 137Cs beta window source in a 10 µR/hr background field, in accordance with the FEMA standard. The Model 52 can be powered by 120 Vac, six “D” cell batteries, or 220 Vac-powered units, which are available as a special order.

The instrument has a “person-counter” integrated into the electronics that increments by one every time a count is completed. It is a four-digit number normally displayed on the LCD display, next to the “READY” message. It also has an RS-232 port that can be used to print out parameter setpoints, background counts, and counts above background.

The portal frame incorporates an array of 18 Geiger-Mueller (GM) detectors positioned around the frame and base. Fourteen GM pancake detectors are located in the frame for monitoring the head and body.  Four cylindrical GM detectors are utilized in the base for monitoring the feet.The electronics are microprocessor-based for ease of setup and reliability. Individual LEDs (Light Emitting Diodes) mounted in the frame and also on the electronics front panel indicate the specific alarm location. LEDs in the front panel indicate count cycle status. Audible signals accompany the LEDs for additional indication. Detector counts, background, and all parameters may be viewed on the LCD display. All setup is accomplished via pushbuttons on the electronics assembly.

The Model 52 incorporates a summing alarm in addition to the individual channel alarms. This increases the system sensitivity to widespread contamination. If two or more channels have a noticeable increase in counts but do not exceed their alarm threshold, the sum of their counts could exceed the summing alarm.

The Model 52 also has background update and subtract capabilities. The instrument will take a background count and subtract it from the current count. This function helps compensate for fluctuations in background. Background subtract can be turned on or off, the background count time is adjustable, and the background interval time is adjustable. The operator can force the instrument to stop and take a background count at a different interval if desired.

The Model 52 is supplied with a polypropylene weather sleeve to protect against wet weather conditions. Units are also supplied with a rugged, wheeled, and padded transport/storage case for rapid deployment.

Indicated Use Portable personnel monitor (primarily beta sensitive) is designed for ease of transport, can be assembled or disassembled in less than five minutes, and includes a carrying case.
Sensitivity This instrument will detect the beta gamma emissions from a 1 μCi 137Cs source when it is located at mid-frame of the portal monitor in a 10 μR/hr background (per the suggested standard in FEMA report “Contamination Monitoring Standard for a Portal Monitor Used for Emergency Response”, Sept 1992).
Energy Response Energy dependent
Body and Head Detectors 14 ea. GM pancake detectors (2 per channel)
Active Area: Approximately 15.4 cm2 (2.4 in2) per detector
Open Area: Approximately 12.2 cm2 (1.9 in2) per detector
Window: 1.7 ± 0.3 mg/cm2 mica
Shoe Detectors 4 ea. (2 per shoe) cylindrical GM detectors
Wall Thickness: 37 ± 7 mg/cm2 stainless steel
Active Length: Approximately 22.9 cm (9 in.)
Sensitivity: 8800 cpm per mR/hr (137Cs)
Display and Control Unit Display: LCD, 1 line x 16 characters
Menu Controls: Select, Save, Exit, Increment Value, Decrement Value
LED Indicators
  • Ready: Green LED, indicates system is ready for use
  • Counting: Green LED, indicates count is in process
  • Check OK: Green LED, indicates count is completed and no alarms sensed
  • Incomplete/Updating: Amber LED, indicates user stepped off portal before count was complete, or that a background update is in progress
  • Low BAT/Trouble: Red LED, indicates a low battery or high/low background
  • Sum Zones: 8 zones with 3 on the left, 3 on the right, 1 for the head, and 1 for the feet; LEDs are situated around a graphic indicating the relative position to the person
Key Operating Parameters Adjustable by administrator with password input

  • Background Count Time: Can be set at any point from 0 to 99 seconds
  • Count Time: Adjustable from 1 to 60 seconds
  • Forced Background Update: Adjustable from 0 to 99 minutes
  • Alarm Hold Time: 1 to 99 seconds
Audio Built-in unimorph speaker with adjustable volume output via menu control
Interface RS-232 port for connection to printer
Power 95 to 135 Vac (178 to 238 Vac available), or 6 each “D” cell batteries
Battery Life Typically 80 hours in a non-alarm condition
Construction Aluminum housing with beige powder coat paint
Weather Protection Crystal clear polypropylene tubing is provided to sleeve over monitor whenever protection against wet weather conditions is desired.
Portal Dimensions (H x W x L) 203.2 x 104 x 43.2 cm (80 x 41 x 17 in.)
Portal Inside Dimensions (H x W) 194.3 x 81.3 cm (76.5 x 32 in.)
Transport Case High-density plastic with wheels and dual padded handles
Transport Case Dimensions (H x W x L) 97 x 61 x 30.5 cm (38 x 24 x 12 in.)
Weight 29.5 kg (65 lb)
Shipping Weight 42.3 kg (93 lb)

Additional information

Weight 100 lbs
Dimensions 38 × 24 × 12 in