Model SP1400DD


  • Ultra-Sensitive Portable Tritium Air Monitor
  • Extremely stable and sensitive
  • Coaxial gamma compensation (1,400cc volume) with virtually no offset in fields up to 15 mR/h
  • Sensitivity: 1 µCi/m3 or 0.04 MBq/m3 with a resolution of ±0.5 µCi/m3 (0.02 MBq/m3)
  • Range: 1 to 19,999 µCi/m3 or 0.01 to 199.99 MBq/m3
  • Audible and visual alarm indicators for low flow, low battery, and signal level
  • Alpha pulse suppression, radon rejection
  • Offset potentiometer control included
  • CE Marked


The Model SP1400DD is Overhoff’s most sensitive portable tritium in air monitor, utilizing dual 1,400cc ionization chambers, one for measurement and one for compensation for the best sensitivity available in a portable tritium monitor.  The chambers were selected to be of a manageable size and weight to carry while achieving maximum performance.  A shoulder strap frees both hands for directing the sniffer hose when the instrument is used for leak detection or other purposes, and a front-panel cover that attaches with two draw latches serves to stow the carrying strap, sniffer hose, and spare dust filters to make it convenient for carrying the instrument to location.  A heavy-duty internal pump provides up to 4 volume changes per minute to ensure a fast overall response and has been rated for 2,000 hours MTBF.  The sensitivity of the SP1400DD exceeds that of most “fixed” monitors, and can therefore be used as a semi-permanent area monitor.

Power is supplied by six “D” size NiMH rechargeable batteries and an external AC adapter is furnished to recharge the batteries.  Onset of the battery depletion is signaled by illumination of an LED located next to the meter face.  A ten-position alarm level stepped attenuator, adjustable from 0 – 50% of full scale 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).  The alarm is latching and a toggle switch enables the operator to reset the alarm once the measured tritium activity has dropped below the setpoint.  The toggle switch has an OFF position which can be used to mute the audible alarm.

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 SP1400DD 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 (±100VDC).  The SP1400DD includes proprietary radon recognition and elimination circuitry to provide accurate, fast, and drift-free measurement.

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