Model 200SB-HTO


  • Lightweight, compact portable tritium air monitor
  • Measures tritium oxide (HTO) only
  • Fast response: 20 seconds to reach 90% of final value
  • Rapid warm-up of less than 30 seconds
  • Coaxial gamma compensation (200cc volume)
  • Medium sensitivity: 10 µCi/m3, 1 MPCa, or 0.4 MBq/m3
  • Wide range: 10 to 199,990 µCi/m3, 0.1 to 1,999.9 MBq/m3, or 1 to 19,999 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 200SB-HTO is a low-cost, lightweight, portable tritium in air monitor designed to measure tritium oxide (HTO) only, even in the presence of other radioactive gases such as noble gases, as well as background gamma.  A rapid warmup, high-volume rotary vane pump, and fast electronics combine to give this tritium monitor a very quick overall response.  Meter readings will reach 90% of the final value within just 5 seconds to a step response of aspirated tritium.  The Model 200SB-HTO uses two coaxial 200cc ionization chambers, one for measurement and one for gamma compensation.  A desiccant column is interposed between the measurement and compensation chambers to provide a differential measurement proportional to HTO only.  The 200SB-HTO is our economy model, with medium sensitivity, a wide range, and fast response.

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 200SB-HTO 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 200SB-HTO includes proprietary radon recognition and elimination circuitry to provide accurate, fast, and drift-free measurement.

The Model 200SB-HTO includes 6 hose connections which can be adjusted for two operating modes to measure either:

  • Total Tritium (HT, HTO, including any other radioactive gases present), or
  • Tritium Oxide (HTO) only, ignoring all other airborne radionuclides such as noble gases and gamma fields.

For HTO measurement, an external desiccant column is interposed between the measurement and compensation chambers which absorbs and removes the HTO to provide a differential measurement that is proportional to HTO only [HTO + other radionuclide – (other radionuclide) = HTO].


Translate »