Analytical Industries GPR-2500 Series Oxygen Transmitter - Manual (Page 11)

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Example: As illustrated by Graph A any error, play in the multi-turn span pot or the temperature compensation
circuit, during a span adjustment at 20.9% (air) of full scale range would be multiplied by a factor of 4.78
(100/20.9) if used for measurements of 95-100% oxygen concentrations. Conversely, an error during a span
adjustment at 100% of full scale range is reduced proportionately for measurements of lower oxygen
concentrations.
Recommendation: Calibrating with a span gas approximating 80% of the full scale range one or two ranges
higher than the full scale range of interest is recommended for 'optimum calibration accuracy'. Always calibrate at
the same temperature and pressure of the sample gas stream.
Start-up
The GPR-2500/2500MO Oxygen Transmitters has been calibrated at the factory prior to shipment and is fully
operational from the shipping container. The ppm oxygen sensor has been removed and packaged in a nitrogen
atmosphere to assure optimum performance. Once installed, we recommend the user allow the transmitters to
stabilize for 30 minutes and then recalibrate the device as instructed below.
Installation Considerations:
The GPR-2500/2500MO consists of an electronic module, sensor housing and sample 1/8” sample inlet and vent
connections housed in a 4”W x 9”H x 3”D enclosure NEMA 4 rated enclosure suitable for wall mounting.
For optimum accuracy zero and calibrate a ppm transmitter after it has been allowed to stabilize, typically 24-36
hours after installation. Assuming the initial zero is performed according to the procedure described herein, the
analyzer should not require zeroing again until the either the sensor is replaced or a change is made to the sample
system or gas lines. Following the initial zero and calibration, the analyzer should not require span calibration again
for up to 3 months under “normal” application conditions as described in the published specifications.
Note: As described below, zeroing the transmitter is recommended for measurements below 1 ppm. The low end
sensitivity (zero capability) has been verified at the factory; however, no ZERO OFFSET adjustment has been
made. A factory adjustment would be meaningless because of the difference in sample systems and leakage
factors between the factory set-up and the actual application conditions
¾ Assemble the necessary hardware for mounting the transmitter and optional components - such as coalescing
or particulate filters and pumps, 1/8” metal or plastic tubing for interconnecting the transmitter and optional
components.
¾ Review the application conditions to ensure the sample is suitable for analysis.
¾ Temperature: The sample must be sufficiently cooled before it enters the transmitter and any optional
components. A coiled 10 foot length of ¼” stainless steel tubing is sufficient for cooling sample gases as high
as 1,800ºF to ambient.