Analytical Industries GPR-2500 A Oxygen Analyzer User Manual
Page 20
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Span Gas Preparation
One of the most accurate, reliable and inexpensive means of calibrating the GPR-2500A is to expose the sensor to
the 20.9% oxygen content found in ambient air. However, exposing the sensor to ambient air with the GPR-2500A
flow through configuration requires opening the enclosure and unscrewing the sensor from its flow housing.
However, many users opt to calibrate with a certified span gas which requires additional components and time.
Caution: Do not contaminate the span gas cylinder when connecting the regulator. Bleed the air filled regulator
(faster and more reliable than simply flowing the span gas) before attempting the initial calibration of the
instrument.
Required components:
¾ Certified span gas cylinder with an oxygen concentration, balance nitrogen, approximating 80% of the full scale
range above the intended measuring range.
¾ Regulator to reduce pressure to between 5 and 30 psig.
¾ Flow meter to set the flow between 1-5 SCFH,
¾ 2 lengths of 1/8” dia. Tygon tubing measuring 4-6 ft. in length.
¾ Suitable fittings and 1/8” dia. Tygon tubing to connect the regulator to the flow meter inlet
¾ Suitable fitting and 1/8” dia. Tygon tubing to connect from the flow meter vent to tube fitting designated
SAMPLE IN on the GPR-2500A.
Procedure:
1. With the span gas cylinder valve closed, install the regulator on the cylinder.
2. Open the regulator’s exit valve and partially open the pressure regulator’s control knob.
3. Open slightly the cylinder valve.
4. Loosen the nut connecting the regulator to the cylinder and bleed the pressure regulator.
5. Retighten the nut connecting the regulator to the cylinder
6. Adjust the regulator exit valve and slowly bleed the pressure regulator.
7. Open the cylinder valve completely.
8. Set the pressure between 5-30 psig using the pressure regulator’s control knob.
Caution: Do not exceed the recommended flow rate. Excessive flow rate could cause the backpressure on the
sensor and may result in erroneous readings and permanent damage to the sensor.