Analytical Industries GPR-2000 ATEX Portable Oxygen Analyzer - Manual (Page 25)

Advanced Instruments Inc.
25
Sampling
Analyzers (GPR-2000) without the optional integral sampling pump: Require positive pressure to flow the sample gas by the
sensor to measure the oxygen concentration in a sample gas.
Analyzers (GPR-2000P) equipped with the optional integral sampling pump: Place the sampling pump’s toggle switch in the ON
position to draw the sample gas into the analyzer or place the sampling pump’s toggle switch in the OFF position and follow the
GPR-2000 procedure above.
Prematurely zeroing the analyzers can cause the analyzers to display a negative reading in both the ZERO and SAMPLE modes.
Procedure:
Following calibration the analyzer returns to the SAMPLE mode after 30 seconds.
1. Select the desired sampling mode - auto-ranging or if manual, the range that provides maximum resolution.
2. Select the appropriate tubing - Tygon tubing is recommended – to transport the sample gas to the analyzer.
3. The main consideration is to ensure the sample gas tubing connections fit tightly over 50% of the inlet fitting or are
reinforced with tie wraps, recommended, to eliminate air leaks which can affect oxygen measurements above or below the
20.9% oxygen concentration in ambient air.
4. Assure there are no restrictions in the sample line.
5. Refer to the section on Pressure & Flow to determine the appropriate Application Pressure considerations.
6. For sample gases under positive pressure the user must provide a means of controlling the inlet pressure between 5-30
psig and the flow of the sample gas between 1-5 SCFH, a flow rate of 2 SCHF is recommended
7. For sample gases under atmospheric or slightly negative pressure the optional GPR-2000P configuration with integral
sampling pump is recommended to draw the sample into the analyzer. Generally, no pressure regulation or flow control
device is involved.
¾ Caution: If the analyzer is equipped with the optional sampling pump, GPR-2000P Series, and is intended for use
in both positive and atmospheric/slightly negative pressure applications where a flow meter valve is involved –
ensure the valve is completely open when operating the sampling pump.
¾ Activate the sampling pump by placing the toggle switch located on the front panel in the ON position.
¾ Note: Expect approximately 8-10 hours service from a single battery charge when using the pump on a regular
basis.
8. Assure the sample is adequately vented for optimum response and recovery – and safety.
9. Allow the oxygen reading to stabilize for approximately 10 minutes at each sample point.
To avoid erroneous oxygen readings and damaging the sensor:
¾ 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).
¾ Assure there are no restrictions in the sample or vent lines
¾ Avoid drawing a vacuum that exceeds 14” of water column pressure – unless done gradually
¾ Avoid excessive flow rates above 5 SCFH which generate backpressure on the sensor.
¾ Avoid sudden releases of backpressure that can severely damage the sensor.
¾ Avoid the collection of particulates, liquids or condensation collect on the sensor that could block the diffusion of oxygen
into the sensor.
Standby
The analyzer has no special storage requirements.
1. The sensor should remain connected during storage periods.
2. Store the analyzer with the power OFF.
3. If storing for an extended period of time, charge before operating.