Analytical Industries GPR-2500 A Oxygen Analyzer - Manual (Page 7)

7
5 Operation
Principle of Operation
The GPR-2500A oxygen transmitter incorporates a variety of advanced galvanic fuel cell type sensors. The
transmitter is a compact efficient package configured with the oxygen sensor and separate circuits boards for
signal processing and terminals for incoming power, power supply, signal output and alarm relay contacts housed
in a general purpose NEMA 4X rated enclosure.
Advanced Galvanic Sensor Technology:
The sensors 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 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. Sample oxygen is analyzed very accurately. Response time of 90% of
full scale is less than 10 seconds (actual experience may vary due to the integrity of sample line connections, dead
volume and flow rate selected) on all ranges under ambient monitoring conditions. Sensitivity is typically 0.5% of
full scale low range. Oxygen readings may be recorded by an external device via the 0-1V signal output jack.
The circuit for the 4-20mA signal output and two adjustable alarms is powered by a DC/DC transformer that
requires a 12-36VDC power source and separate wiring for the outputs. A loop power source is not sufficient to
power to the circuit. The 4-20mA output is also represented on full scale oxygen readings to an external device.
Sample System:
The GPR-2500A is supplied without a sample conditioning system thereby giving users the option of adding their
own or purchasing a factory designed sample conditioning system. Whatever the choice, the sample must be
properly presented to the sensor to ensure an accurate measurement. Users interested in adding their own sample
conditioning system should consult the factory. Advanced Instruments Inc. offers a full line of sample handling,
conditioning and expertise to meet your application requirements. Contact us at 909-392-6900 or e-mail us at
[email protected]