Model Triathalon-H3


  • Continuous Tritium Air Monitor
  • NEMA-4X/IP-66 wall-mount enclosure with lock and key
  • Optional totalizer for computing total tritium release from stacks and other effluents
  • Smart, microprocessor driven with onboard data logging and custom software
  • Total tritium (HT + HTO) or HTO only measurement
  • Two tritium level alarms (alert and high), malfunction alarm, and low flow alarm included
  • Gamma compensation (2L)
  • Visual alarm indicators for signal level, low flow, and malfunction
  • Alpha pulse suppression, radon rejection
  • Long-term zero stable, span calibration is permanently stable due to special electrometer design


The Model Triathalon-H3 is a single-range ionization chamber tritium in air monitor housed in a NEMA-4X wall-mount enclosure designed for stack or room monitoring applications.  This smart instrument includes a microprocessor, color LCD touch-screen display, and custom software with on-board datalogging.  The subtractive balanced chamber electrometer circuit and radon rejection decreases background to negligible levels.  The software allows you to adjust units of measurement, alarm limits, and flow rate for totalizing, among other parameters.  An upgraded alarm system provides two adjustable level alarms (alert level and high level), as well as alarm indicators for low flow and low/high voltage power supply failure.  Level alarms can be configured for latching or non-latching operation.

The Triathalon-H3 includes a desiccant column so that it can be configured to measure either HTO only, or total tritium (HTO + HT) which is also used for gas calibration.

The NEMA-4X/IP-66 wall-mount enclosure is designed for continuous duty and the clear polycarbonate window protects all front panel components while still allowing visual inspection.  The door is hinged to allow servicing of components, and also includes a lock with key to prevent unauthorized access.  External sample connections are 3/8″ O.D. stainless steel Swagelok fittings.  Alarm relays for the two level alarms and malfunction alarm are included.

An optional totalizer feature can be included which computes the total tritium concentration released up the stack or effluent by multiplying the stack flow rate (manual or dynamic from stack flow sensor) by the measured tritium concentration.  The Triathalon-H3 is a cost-effective tritium effluent monitor that is compact, lightweight, and includes an easy wall-mount configuration.

The only maintenance required for the Triathalon-H3 is periodic service of the pump and replacement of the dust filter.  The sensitivity, accuracy, and noise level of the Model Triathalon-H3 is superior to competitive instrumentation by an order of magnitude.

Calibration of the Triathalon-H3 tritium monitor can be accomplished by three different methods:

  1. Tritium gas calibration: Injecting tritium gas into the ionization chambers to produce an accurately predictable concentration and adjusting the calibration potentiometer accordingly. Overhoff offers factory calibration services and also provides tritium gas calibrators for the customer to calibrate on-site.
  2. Gamma calibration using a gamma source: Using a certified gamma range or source, tritium monitors can be calibrated using the relationship 1mR/hr yields the same ionization current as 90 µCi/m3 of tritium.
  3. Electrical equivalence method: All Overhoff ionization chamber – electrometer modules carry a BNC receptacle to which a precisely calibrated ultra-high resistor can be attached. Using Ohm’s law and knowing the volume of the ion chamber, you can calculate the current value and expected panel meter display and adjust the calibration potentiometer as required.  Calibration resistors are available for purchase.
Translate »