The Model 2×200-LD is Overhoff’s portable tritium in air “leak detector” which has the unique ability to measure for tritium compounds (T2O/HTO) and elemental tritium (T2), in real-time, while providing gamma compensation. A front panel toggle switch allows you to select which channel (T2 or T2O) is displayed. The required radiological protection for tritium compounds is much higher than that for elemental tritium. Elemental tritium will combine readily with oxygen to form tritium oxide and will also replace hydrogen atoms in compounds. The presence of elemental tritium in the working environment is an indication of a current leak in the system or container, and the Model 2×200-LD can be used to rapidly locate and secure the source of leakage. Gamma response is less than 0.2 µCi/m3 per mR/h for any field direction. Four 200cc ion chambers arranged in a cruciform geometry provide nearly perfect gamma compensation regardless of photon energy, flux gradient, or flux direction.
Power is supplied by a pair of “D” size NiMH rechargeable batteries. Onset of the battery depletion is signaled by illumination of an LED located next to the meter face. This same LED will also signal red when there is a malfunction with the high voltage power supply. A nine-position alarm level stepped attenuator, adjustable over partial scale (2 to 1,000 µCi/m3) 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 2×200-LD 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 (±80VDC). The 2×200-LD includes proprietary radon recognition and elimination circuitry to provide accurate, fast, and drift-free measurement.
|MEASUREMENT RANGE||Available in the following ranges:|
i) 1 to 19,999 µCi/m3, basic sensitivity of the order of 5 µCi/m3
ii) 0.1 to 1,999.9 MBq/m3 or DAC
iii) 1 to 19,999 μSv/h
|T2 AND T2O MODES||Two channel measurement, switch selectable|
|ACCURACY, SPAN||±10 % of reading, ±2 µCi /m3, whichever is greater|
|NOISE LEVEL AND ZERO STABILITY||± 2 µCi/m3 (10 second electronic time constant); ±2 µCi /m3 long term|
|GAMMA COMPENSATION||multiple chambers arranged in cruciform pattern to completely eliminate errors due to external gamma radiation. Gamma response less than 0.2 μCi/m3 per mR/hr for any field direction|
|ALPHA PULSE SUPPRESSION||a circuit provides recognition and cancellation of undesirable noise spikes due to airborne radon|
|RESPONSE RATE||30 seconds to reach 90% of final reading|
|ALARM (ACOUSTIC)||1. Ten position stepped attenuator set point for signal alarm|
2 – 1,000 µCi/m3, steady tone. An OFF position is included.
2. Low flow produces an intermittent tone
3. Mute switch silences audible tone
|ALARM (VISUAL)||signal level: red LED, when tritium exceeds setpoint|
low flow: yellow LED, flashing, low pump flow
low battery: red LED
HVPS: red LED illuminates to indicate a malfunction with the high voltage power supply (HVPS) used to bias the ionization chambers
|EXTERNAL CONNECTIONS||mini DIN plug for output signal, and for alarms|
|IONIZATION CHAMBER VOLUME||effective volume: 200 cm3; port to port volume: 660 cm3|
|DUST FILTER||HEPA, in-line disposable cartridge, Pall P/N 12082|
|PUMP AND FLOW RATE||internal rotary vane pump, flow rate nominally 1.5 – 2 LPM|
|ENVIRONMENTAL||0° C to +40° C, 20 – 90 % relative humidity, non-condensing|
|BATTERIES||two “D” size NiMH batteries, 10,000 mAh|
external jack for supplementary power input and charging
|POWER CONVERTER||100-240 VAC, 50/60 Hz, .25 A to 3.3 Vdc @ 1.2 A|
5.5 mm O.D. x 2.1 mm I.D. Plug, center pin is positive
|SIZE AND WEIGHT||7.6″ [193mm] L x 5.2″ [132mm] W x 6.9″ [175mm] H excluding handle, 6.5 lbs (3 kg)|
|DESICCANT COLUMN||Clear poly carbonate cartridge of indicating desiccant|
|Accessories include:||2 “D” size NiMH batteries (installed), sniffer hose, dust filter, 2.3 meter long cable with Mini-DIN plug for J2 output connector at one end, power converter 100-240VAC, and two desiccant columns filled with silica gel.|