PTM-1812 Handheld Tritium Monitor

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The PTM-1812 Handheld Tritium Monitor

Premium, truly portable instrumentation at a fair price

The femto-TECH Model PTM-1812 Hand Held Tritium Monitor is a precision airborne beta radiation detection instrument that serves as two instruments in one. The user can select between a perforated ion chamber shell for passive sampling or a solid ion chamber shell for active sampling. Both ion chamber shells are supplied with the instrument and are easily exchangeable in the field. In the passive configuration the PTM-1812 serves as a continuous real-time area monitor. In the active configuration, it uses an internal pump to pull samples from tritium containers, glove boxes, etc.

The intrinsic calibration of the ion chamber used in a PTM-1812 system is established by the physical size and geometry of the ion chamber and the value of the feedback resistor (high-meg). The National Institute of Standards and Technology (NIST) traceable tritium gas standards have been used to verify the electronic calibration factor for this type of ion chamber. Production ion chambers maintain the same parameters as those that have been calibrated with the tritium gas standard, therefore, the production ion chambers have the same intrinsic calibration. The feedback resistor of each production unit is measured once by the supplier of the resistors and a second time at femto-TECH. NIST traceable resistor standards and voltmeters are used to perform this measurement. A built-in electronic calibration adjustment provides field adjustment and calibration verification of all electronic components back to the feedback resistor. Field calibration checks can also be performed using a fixed geometry gamma source to provide a known amount of ionization in the ion chamber.


Shell is constructed of rugged steel

Ion chamber is constructed of 304 stainless steel

Torlon insulator

Convenient control panel features

Easily transportable to & from testing sites

Active or Passive sampling

NIST traceable calibration

Background & Calibration conducted by manufacturer

Available with both active and passive chamber configurations.


Radiation HT and HTO beta (18.6keV peak, 5.7 keV average), gamma, alpha.
Detector Air Ionization Finned Electrode Probe (in solid or perforated chamber).
Dimensions 4.2"W x 4.0"H x 12.0"L (10.7 cm x 10.2 cm x 30.5 cm)
Weight 7½ lbs. (3.4 kg)
Chamber Volume 180cc (sensing), 375cc (total)
Dynamic Range 0 to 20,000 µCi/m³ in one continuous linear range.
Sensitivity 1 µCi/m³
Accuracy ±10% of reading (in air at 760 torr and 20°C) Note: Concentration measurement is a function of temperature through the PVT gas law.
Power 12 VDC rechargeable batteries will operate continuously for 7 days in the passive mode with the pump off. The pump battery will operate continuously for up to 2 days. Instrument can be operated while connected to included charger.
Display 4½ digit LCD with 0.4" high digits (1 cm)
access_alarmAlarm Audible and visual, adjustable over entire range and read on display. Silenced from control panel rocker switch.
Alarm Set 10 turn potentiometer that permits the alarm level to be adjusted on the digital panel meter while the alarm read switch is depressed.
Zero Rocker switch which activates the electrometer zero by bypassing the high meg resistor.
Zero Adjust 10 turn potentiometer that adjusts the setting of the electronic zero on the digital panel meter while the zero switch is depressed.
Instrument Test Rocker switch to activate current injection which tests all electronics and indicates proper operation on display.
Battery Test Rocker switch to test Electrometer (A) or pump (B) battery.
Pump Rocker switch enables built in pump for grab sample testing.

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