Analytical Industries GPR-3100 Series Oxygen Purity Analyzer - Manual (Page 9)

Advanced Instruments Inc.
5 Operation
GPR-3100 Rev 2/05 2
With the sensor and sample gas lines temperature controlled and the signal output of the sensor
compensated for ambient pressure variations it was possible to measure oxygen in the suppressed range
of 90-100% with less than +1% of full scale (+0.1% oxygen) accuracy. The calibration was checked
periodically and found to be within +1% of full
scale over the fourteen month test period
suggesting the interval between calibrations
could be extended to several months.
To demonstrate the stability of the new
analyzer, 99.5% oxygen was introduced
(typically the threshhold for gas manufacturers)
for 30 days and the output plotted as shown at
the right. The resolution of the analyzer’s 4-1/2
digit display is 0.01%.
The maximum variation in the signal output is
+0.1% oxygen over a 24 hour period and is
primarily to the variation in ambient
temperature.
Advanced Sensor Technology Overview:
The sensor function on the same principle and are specific for oxygen. They measure the partial pressure
of oxygen from low ppm to 100% levels in inert gases, gaseous hydrocarbons, helium, hydrogen, mixed
gases, acid gas streams and ambient air.
Oxygen, the fuel for this electrochemical transducer, diffusing into the sensor reacts chemically at the
sensing electrode to produce an electrical current output proportional to the oxygen concentration in the
gas phase. The sensor’s signal output is linear over all ranges and remains virtually constant over its
useful life. The sensor requires no maintenance and is easily and safely replaced at the end of its useful
life.
Proprietary advancements in design and chemistry add significant advantages to an extremely versatile
oxygen sensing technology. Sensors for low ppm analysis recover from air to ppm levels in minutes,
exhibit longer life and reliable quality.
The expected life of our new generation of percentage range sensors now range to five and ten years
with faster response times and greater stability. Another significant development involves expanding the
operating temperature range for percentage range sensors from -30°C to 50°C.
Electronics:
The signal generated by the sensor is processed by state of the art low power micro-processor based
digital circuitry. The first stage amplifies the signal. The second stage eliminates the low frequency noise.
The third stage employs a high frequency filter and compensates for signal output variations caused by
ambient temperature changes. The result is a very stable signal.
Additional features of the micro-processor based electronics include manual or auto ranging, optional
integral sample, span and zero inlet valves for auto-zero and auto-calibration at user specified intervals,
data acquisition and temperature tracking all which can be controlled remotely. Analog outputs, 0-1V and
an isolated 4-20mA, and an USB communication link are provided along with field selectable alarms with
dry relay contacts, power and range identification. An unique algorithm predicts and display a message
indicating a ‘weak sensor’ suggesting the sensor be replaced in the near future.
9 0 .0 0
9 1 .0 0
9 2 .0 0
9 3 .0 0
9 4 .0 0
9 5 .0 0
9 6 .0 0
9 7 .0 0
9 8 .0 0
9 9 .0 0
1 0 0 .0 0
2 5 8 1 1 1 4 1 7 2 0 2 3 2 6 2 9
% O
xy
ge
n
Da y s
30 Day Stability in
99.5% Oxygen
90-100% Suppressed Range