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5. TRANSDUCER AND TEMPERATURE COMPENSATION
The Micro-Fuel Cell has an inherent positive temperature coefficient, the effects of which have
been minimized through the implementation of a thermistor compensation circuit.
Internal electronic calibration is accomplished by TAI. However, should there by any doubt, the
following procedure can be used to recalibrate the electronics. Refer to Schematic.
1. Disconnect cell.
2. Move range switch to “CAL” position.
3. Adjust R2 (designated as R2 on Schematic C70246 (C70248 for 311TCXL) and
designated on the A3 PCB
module assembly as R28) for 0 ± 1 mV at output of A3, pin 6.
4. Verify that the offset is the same on all ranges.
5. Re-connect cell.
6. LEAK TESTING
If a leak is suspected in the unit, DO NOT ATTEMPT TO TIGHTEN THE
DISCONNECT FITTINGS. THE FITTINGS ARE POTTED IN EPOXY AND
TIGHTENING THEM WILL BREAK THE SEALS.
To check for leaks, TAI recommends one of the following procedures:
Procedure I:
1. Purge the instrument down as low as possible.
2. Place the vent line in water and disconnect the sample.
3. Next, disconnect the vent line and place the range switch on the X1000 range.
4. The unit should stay on the X1000 range if there are no leaks.
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Procedure II:
1. Purge the instrument with Nitrogen at the sample port.
2. Note the reading once it has stabilized (at least 24 hrs. on the 0-2 ppm range) and
increase the flow rate.
3. If the reading goes down, the unit, or the tubing to the unit, has a leak.