Analytical Industries GPR-3500 MO Portable Oxygen Analyzer - Manual (Page 12)

Advanced Instruments Inc.
12
¾ When certified span gas is not available to calibrate a ppm analyzer (immediately following air calibration reintroduce a gas with a
low oxygen concentration to expedite the return to ppm level measurements as described above **).
Mounting the Analyzer
Normally mounting a portable analyzer is not a consideration. However, the GPR-3500 analyzer can operate continuously when
connected to AC power using the appropriate charging adapter. The analyzer enclosure is cast with four (4) holes in the bottom section
specifically intended for mounting to any flat vertical surface.
Gas Connections
The GPR-3500MO with its standard flow through configuration is designed for positive pressure samples and requires connections for
incoming sample and outgoing vent lines. Zero and span inlet ports are offered as part of the optional sample systems. The user is
responsible for calibration gases and the required components, see below.
With the pressure regulated to between 5-30 psig, flow rates of 1-5 SCFH cause no appreciable change in the oxygen reading.
However, flow rates above 5 SCFH generate backpressure and erroneous oxygen readings because the diameter of the integral tubing
cannot evacuate the sample gas at the higher flow rate. A flow indicator with an integral metering valve upstream of the sensor is
recommended as a means of controlling the flow rate of the sample gas. A flow rate of 2 SCFH or 1 liter per minute is recommended
for optimum performance.
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 the sensor (voiding the sensor warranty).
Procedure:
1. Caution: Do not change the factory setting until instructed to do in this manual.
2. Designate one of the bulkhead tube fittings as the VENT and the other SAMPLE.
3. Regulate the pressure as described in Pressure & Flow above.
4. Connect a 1/8” vent line to the compression fitting to be used for venting the sample.
5. Connect a 1/8” ZERO, SPAN or SAMPLE line to the fitting designated SAMPLE.
6. If equipped with optional fittings and/or sample system, connect the ZERO and SPAN gas lines.
7. Allow gas to flow through the portable oxygen purity analyzers and set the flow rate to 2 SCFH.
Output connection:
The analyzer provides a 0-1V full scale with negative ground signal output for external recording devices.
Procedure:
1. Connect the lead wires from the external recording device to the male phone plug supplied with analyzer. (Note: Connect the
positive lead to the center terminal of the male phone plug.)
2. Insert the male phone plug into the integral female OUTPUT jack located on the side of the enclosure.