Advanced Instruments Inc.
Installation
Gas Sample Stream: Ensure the gas stream composition of the application is consistent with the specifications of
the analyzer/sensor and review the application conditions before initiating the installation. Consult factory 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
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 sensor warranty if not identified at time of
order placement. Consult factory for recommendations concerning the proper selection and installation of
scrubber/filter components.
Expected Sensor Life
With reference to the publish specification located as the last page of this manual, the expected life of all oxygen
sensors is predicated on the basis of oxygen concentration (< 10,000 PPM), temperature (77°F/25°C) and pressure
(1 atmosphere) in “normal” applications. As a rule of thumb sensor life is inversely proportional to changes in the
parameters. Deviations of the gas concentration and or temperature outside of the specifications will affect the life of
the sensor. Avoid exposure to oxygen levels above 1% (10,000 PPM) for hours at a time.
Failure to do so may result in damage to the sensor(s) as follows:
GPR Series PPM sensors – reduced sensor life and loss of low end sensitivity when exposed continuously to
20.9% oxygen; sensor will last approximately 6-8 months and may develop a low end offset > 1-2 PPM
XLT Series PPM sensors - reduced sensor life and loss of low end sensitivity (XLT sensor exposed
continuously to the 20.9% O2 content of air will last approximately 7 days).
Accuracy & Calibration
Refer to section 5 Operation. The 0-25% Range is provided only for the purpose of air calibration which is
recommended only if span gas is not available. Bringing the analyzer back online after calibration with the 20.9%
oxygen content of air, takes longer than calibrating the analyzer with a span gas, for example, 80 PPM oxygen.
Materials
Assemble the necessary zero, sample and span gases and optional components such as valves, coalescing or
particulate filters, and pumps as dictated by the application; stainless steel tubing is essential for maintaining the
integrity of the gas stream for PPM measurements.
Operating Temperature
The sample must be sufficiently cooled 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. The
maximum recommended operating temperature is 45º C. On an intermittent basis, unless the user is willing to accept
a reduction in expected sensor life – refer to analyzer specification, the analyzer may be operated at 50 degree
o
C. At
temperatures above 25
o
C, the user can expect a reduction in sensor life of ~ 2.5% per degree increase in
temperature. As an example, if the analyzer is continuously operated at 35
o
C, the expected sensor life will be
reduced by ~25%.
Pressure and Flow
All electrochemical oxygen sensors respond to partial pressure changes in oxygen. The sensors are equally capable of
analyzing the oxygen content of a flowing sample gas stream or monitoring the oxygen concentration in ambient air
(such as in a confined space in a control room or an open area such as a landfill or bio-pond).
Sample systems and flowing gas samples are generally required for applications involving oxygen measurements in a
gas mixture. For sub PPM measurements, the use of stainless steel tubing and fittings is critical to maintaining the
integrity of the gas stream to be sampled. Further, the inlet sample pressure must always be higher than the
pressure at the outlet vent, which is normally at atmospheric pressure.
To analyze a gas stream, the gas must flow or be drawn through the sensor housing. The internal sample system of
the analyzer may include sample/bypass valves, shut off valve, a flow control (please check the QC sheet to ensure
the included sample system), a flow indicator and a stainless steel sensor housing with an o-ring seal to prevent the
leakage of air into the sensor housing.
6
