Model 2x200-LD


  • Portable tritium air monitor for measuring T2 and T2O/HTO simultaneously
  • Measures both elemental tritium (T2) and tritium oxide (T2O/HTO) in real-time
  • Front panel toggle switch selects whether T2 or T2O is displayed
  • Cruciform gamma compensation
  • Sensitivity: 5 µCi/m3, 0.2 MBq/m3
  • Range: 1 to 19,999 µCi/m3 or 0.1 to 1,999.9 MBq/m3 (DAC, MPCa, and µSv/h also available)
  • Audible and visual alarm indicators for low flow, low battery, and signal level
  • High voltage power supply malfunction alarm
  • Alpha pulse suppression, radon rejection
  • Offset potentiometer control included
  • CE Marked


The Model 2×200-LD is Overhoff’s portable tritium in air “leak detector” which has the unique ability to measure for tritium compounds (T2O/HTO) and elemental tritium (T2), in real-time, while providing gamma compensation.  A front panel toggle switch allows you to select which channel (T2 or T2O) is displayed.  The required radiological protection for tritium compounds is much higher than that for elemental tritium.  Elemental tritium will combine readily with oxygen to form tritium oxide and will also replace hydrogen atoms in compounds.  The presence of elemental tritium in the working environment is an indication of a current leak in the system or container, and the Model 2×200-LD can be used to rapidly locate and secure the source of leakage.  Gamma response is less than 0.2 µCi/m3 per mR/h for any field direction.  Four 200cc ion chambers arranged in a cruciform geometry provide nearly perfect gamma compensation regardless of photon energy, flux gradient, or flux direction.

Power is supplied by a pair of “D” size NiMH rechargeable batteries.  Onset of the battery depletion is signaled by illumination of an LED located next to the meter face.  This same LED will also signal red when there is a malfunction with the high voltage power supply.  A nine-position alarm level stepped attenuator, adjustable over partial scale (2 to 1,000 µCi/m3) is located on the front panel.  A steady tone is emitted by an acoustic signaler if the measurement exceeds the alarm set-point (illuminates red LED), or if the sample airflow has been interrupted and is too low (illuminates yellow LED).  The alarms are non-latching.

Zero adjustment is unnecessary, the electrometer is completely temperature stable and shows zero drift from 0° C to 50° C due to special design and careful selection of an ultra-high impedance semiconductor with low internal current leakage and long-term DC stability.  The 2×200-LD can reliably measure currents as low as 10-16 amperes and the span calibration is permanently stable.  The ionization chamber polarizing voltage is supplied by an electronic low-noise regulated dual high-voltage power supply (±80VDC).  The 2×200-LD includes proprietary radon recognition and elimination circuitry to provide accurate, fast, and drift-free measurement.

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