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5 Operation
Principle of Operation
The GPR-2500/2500MO oxygen transmitter incorporates a variety of ppm range advanced galvanic fuel cell type
sensors. The transmitter is configured in a general purpose NEMA 4X rated enclosure and meets the intrinsic safety
standards required for use in Class 1, Division 1, Groups A, B, C, D hazardous areas when operated in conjunction
with the manufacturer’s recommended optional intrinsic safety barriers.
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 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. 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.
A 4-20mA signal output is provided from a two-wire 12-36VDC loop power source such as a PLC and is represented
on full scale oxygen readings to an external device. When operated in conjunction with the manufacturer’s
recommended optional intrinsic safety barriers the GPR-2500/GPR-2500MO meets the intrinsic safety standards
required for use in Class 1, Division 1, Groups A, B, C, D hazardous areas.
Sample System:
The GPR-2500/2500MO is supplied without a sample conditioning system for maximum portability. However 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
