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3.1 Introduction. The Model 311XL is supplied completely assembled and ready for
instant use. The Micro-Fuel Cell must be installed prior use. When a sensor is first installed, the
instrument should be purged for 12-16 hours with zero gas (an inert gas such as nitrogen or
argon with less than 0.1 ppm oxygen). This will remove any trace levels of oxygen from the
sensor or the instrument. The integral shut-off valves in the quick disconnect sample fittings, if
not disturbed, will maintain this inert atmosphere within the manifold indefinitely (the
equilibrium concentration of oxygen is normally less than 1000 ppm).
When the range selector is advanced from the “OFF” position, power to the instrument’s
circuitry is established. The meter will constantly respond to the residual oxygen within the
integral sample passages. It is impossible to achieve a “perfect” seal of the internal sample
system, and what the meter is indicating is the diffusion -- consumption balance point of the
internal sample system and the Micro-Fuel Cell. This “balance” point, with a properly calibrated
instrument is always within the limits of the X100 range. If the reading climbs off the limits of
this scale, a leak in the manifold assembly is indicated.
TO EXTEND CELL LIFE AND MINIMIZE THE TIME REQUIRED TO MAKE THE
NEXT ANALYSIS, THE INSTRUMENT SHOULD ALWAYS BE PURGED WITH THE
SAMPLE OR AN INERT GAS PRIOR TO BEING TAKEN OUT OF SERVICE FOR
STANDBY OR STORAGE.
3.2 Calibration. The inherently constant output of the cell during its useful life
precludes a definitive calibration cycle. TAI feels that the interval between calibrations should
be dictated by the customer’s application. If the instrument is being used to certify the oxygen
content of a product for delivery, then, a calibration prior to certification would certainly be in
order. If, on the other hand, the instrument is being used to monitor or guard a sample and the
evidence provided by the analyzer will in themselves determine when a calibration check is in
order. The sensitivity of the analyzer should be checked at two to four week intervals.
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3.2.1 Calibration Procedure.
Gas requirements:
Zero gas: An inert gas (nitrogen or argon) with less than 0.1 PPM oxygen concentration.