Advanced Instruments Inc.
Installation
Considerations
Gas Sample Stream: Ensure the gas stream composition of the application is consistent with the specifications and
review the application conditions before initiating the installation. Consult the factory if necessary to ensure the
sample is suitable for analysis.
Contaminant Gases: A gas scrubber and flow indicator with integral metering valve are required upstream of the
analyzer to remove interfering gases such as oxides of sulfur and nitrogen or hydrogen sulfide that can produce false
readings, reduce the expected life of the sensor and void the sensor’s warranty if not identified at time of order
placement Consult factory for recommendations concerning the proper selection and installation of scrubber
components.
Expected Sensor Life: With reference to the publish specification the expected life of all oxygen sensors is
predicated on oxygen concentration, temperature and pressure (see section 4 for more info). Deviations outside
these specifications will affect the life of the sensor. As a rule of thumb, sensor life is inversely proportional to
changes in the parameters.
Zero Calibration: In theory, the oxygen sensor produces no signal output when exposed to an oxygen free sample
gas. In reality, expect the analyzer to generate an oxygen reading when sampling oxygen free sample gas due to
contamination or quality of the zero gas; minor leakage in the sample line connections; residual oxygen dissolved in
the sensor’s electrolyte; and, tolerances of the electronic components.
Zero calibration is recommended only for online analyzers performing continuous analysis below 5% of the lowest
most sensitive range available with analyzer, e.g. analysis below 0.5 PPM on the 10 PPM range.
Note: Once the zero offset adjustment is made, zero calibration is not required again until the sample system
connections are modified or, when installing a new oxygen sensor.
Determining True Zero Offset: Allow the analyzer approximately 24 hours to stabilize with flowing zero gas as
evidenced by a stable reading or horizontal trend on an external recording device.
Span Calibration: Involves adjusting the analyzer electronics to the sensor’s signal output at a given oxygen
standard, e.g. a certified span gas with an oxygen content (balance nitrogen) approximating 80% of the range of
interest or one range above the intended measuring range is recommended for optimum accuracy.
Recommendation: The inherent linearity of the galvanic oxygen sensor enables the user to calibrate the analyzer with
ambient air (20.9% oxygen) and operate the analyzer within the stated accuracy spec on the lowest most sensitive
range available with the analyzer. However, a certified span gas may be used for calibration (see above).
Air calibrate the analyzer when installing and replacing a new oxygen sensor assures the user that analyzer and
sensor are within the specifications; air calibration failure will alert the user to take immediate steps to correct the
mode of failure (analyzer electronics or sensor/sensor housing).
Temperature: The sample must be sufficiently cooled (within the operating range of the analyzer) before it enters
the analyzer and any optional components. A coiled 10 foot length of ¼” stainless steel tubing is sufficient for cooling
sample gases as high as 1,800ºF to ambient.
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