Model 200SS


  • Lightweight, compact portable tritium air monitor
  • Not gamma compensated, low priced option if gamma compensation is not required
  • Fast response: 15 seconds to reach 90% of final value
  • Rapid warm-up of less than 30 seconds
  • Sensitivity: 3 µCi/m3, 0.1 MBq/m3
  • Range: 1 to 19,999 µCi/m3 or 0.1 to 1,999.9 MBq/m3, DAC, MPCa
  • Audible and visual alarm indicators for low flow, low battery, and signal level
  • Alpha pulse suppression, radon rejection
  • No long-term drift, no manual zero adjustments
  • Offset potentiometer control included
  • CE Marked


The Model 200SS is a low-cost, lightweight, portable tritium in air monitor based off our popular Model 200SB.  The primary difference is that the Model 200SS uses both 200cc ionization chambers for measurement, providing additional detector volume for better sensitivity but eliminating gamma compensation.  Useful for applications that don’t require gamma compensation, allowing you to measure low levels of tritium with a fast response time at a very affordable price.  A rapid warmup, high-volume rotary vane pump, and fast electronics give this instrument a quick overall response.  Meter readings will reach 90% of the final value within 15 seconds to a step response of aspirated tritium.  The Model 200SS uses two coaxial 200cc ionization chambers, both for measurement (no gamma compensation).

Power is supplied by a pair of “D” size alkaline batteries.  Onset of the battery depletion is signaled by illumination of an LED located next to the meter face.  A nine-position alarm level stepped attenuator, adjustable over partial scale (.01 – 5%) 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 200SS 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 a long-life electronic low-noise regulated dual high-voltage power supply (±80VDC).  The 200SS includes proprietary radon recognition and elimination circuitry to provide accurate, fast, and drift-free measurement.

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