Analytical Industries GPR-1900 Series Trace PPB Oxygen Analyzer - Manual (Page 13)

Advanced Instruments Inc.
13
Gas Connections
The GPR-1900 with its standard flow through configuration is designed for positive pressure samples and requires connections
for incoming sample and outgoing vent lines. The user is responsible for calibration gases and the required components, see
below. 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 fitting designated as the vent (it pressurizes the sensor) or 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.
2. Designate the female quick disconnect fittings, right side of the analyzer, as inlet and vent respectively.
3. Regulate the pressure and flow as described in Pressure & Flow above.
4. Install one mating male vent fitting into the female quick disconnect fitting designated as the VENT – connection of 1/8”
dia. metal vent line (requires an 1/8” male NPT to tube adapter) is optional.
5. Connect the second mating male fitting to 1/8” dia. metal sample line using a 1/8” male NPT to tube adapter.
6. Connect the third mating male fitting to 1/8” dia. metal span gas line using a 1/8” male NPT to tube adapter.
7. Install either the sample or span mating male fitting into the female quick disconnect fitting designated as SAMPLE.
8. Set the flow rate to 2 SCFH (open the flow control valve completely if using an external sampling pump positioned
downstream of the sensor).
9. Allow gas to flow through the analyzer for 3-5 minutes and proceed to Calibration or Sampling.
Electrical Connections:
The appropriate AC or DC power requirement must specified be
specified at order placement.
Incoming power for the 100-250V AC powered analyzers is
supplied through a universal power entry module. A standard
computer type power cord (P/N A-1008) is required for the
universal power entry module. DC power cable must be supplied
by the user. A well grounded insulated power cable is
recommended to avoid noise resulting from unwanted
interference. Power consumption is approximately 30 watts.
Filtered terminal blocks are provided for power failure, set point
alarm relays and signal output connections. The PCB also
includes a transformer to power the relays, a sensor bypass
switch for troubleshooting the electronics
Caution: Integral 4-20mA converters are internally powered
and do not require external power. DO NOT supply any voltage
to any of the terminals for 4-20mA signal output and range ID or
the 4-20mA converters will be damaged.
Caution: To assure proper grounding, connect the 4-20mA
signal output to the external device (PLC, DCS, etc.) before attempting any zero or span adjustments.
Procedure:
1. As illustrated above the sensor, power and alarm relays and signal output connections are hard wired to screw type
terminal blocks located at the rear of the analyzer.
2. Use a small bladed screwdriver to loosen the appropriate terminal screws as illustrated above.
3. Strip the wires of the cable no more than 3/16 inch.