Advanced Instruments Inc.
error during a span adjustment at 100% of full scale range is reduced proportionately for measurements of lower
oxygen concentrations.
Mounting the Analyzer
Normally mounting a portable analyzer is not a consideration. However, the GPR-1200 analyzer can operate
continuously when connected to AC power using the factory provided battery charging adapter. The analyzer enclosure
is cast aluminum with four (4) holes in the bottom section specifically intended for wall mounting option.
Gas Connections
The GPR-1200 flow through configuration is designed for positive pressure samples and requires connections to
incoming sample and vent 1/8” diameter tube fittings. The user is responsible for making provision for calibration
gases, see Calibration section of the Analyzer Specification and Installing Span Gas below.
Flow rates of 1-5 SCFH cause no appreciable change in the oxygen reading. However, flow rates above 5 SCFH
generate a backpressure on sensor and cause erroneous oxygen readings (because the 1/8” diameter of the integral
tubing cannot evacuate the sample gas at the higher flow rate quickly). A flow control valve upstream of the sensor
controls the flow rate of the sample gas which is displayed by the flow indicator downstream of the sensor. A flow
rate of 2 SCFH or 1liter per minute is recommended for optimum performance.
Note: For applications where the sample flow is ambient or at a slightly negative pressure (up to 40” of water column
pressure), either the optional integral sample pump or an external sample pump connected to the vent of the
analyzer should be used to draw the sample through the sensor housing.
Caution: Do not place your finger over the vent (it pressurizes the sensor) to test the flow indicator when gas is
flowing to the sensor. Removing your finger (the restriction) generates a vacuum on the sensor and may damage it
(voiding the sensor warranty).
Caution: Before turning the sample pump ON, open the flow control valve completely. Failure to do so will draw
vacuum on the sensor and may cause permanent damage to the sensor.
Procedure
Caution: Do not change the factory setting until instructed to do so, leave the SAMPLE/BYPASS valve in the BYPASS
position.
1.
Locate the sample inlet and vent fittings respectively on the right side of the analyzer.
2.
Regulate the pressure and flow as described in Pressure & Flow above.
3.
Connect the 1/8” dia. metal vent line to the fitting designated VENT.
4.
Connect the 1/8” dia. metal sample gas line to the fitting designated SAMPLE IN.
5.
Set the flow rate to 2 SCFH
Caution: Open the flow control valve completely if using the optional integral or an external sampling pump (pump
positioned downstream of the sensor).
6.
Allow gas to flow through the analyzer for 3-5 minutes in the BYPASS mode to purge air trapped in the sample gas
line before switching the SAMPLE/BYPASS valve to SAMPE.
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