Analytical-industries GPR-1200 ATEX Portable Trace PPM Oxygen Analyzer Manuel d'utilisateur télécharger pdf (Page 20)

¾ Always calibrate at the same temperature and pressure of the sample gas stream.

¾ For 'optimum calibration accuracy' calibrate with a span gas approximating 80% of the full scale range one or a higher

range than the full scale range of interest (normal use) to achieve the effect of “narrowing the error” by moving downscale

as illustrated by Graph A in the Accuracy & Calibration section.

¾ Calibrating with a span gas approximating 5-10% of the full scale range near the expected oxygen concentration of the

sample gas is acceptable but less accurate than ‘optimum calibration accuracy’ method recommended – the method usually

depends on the gas available.

¾ Calibrating at the same 5-10% of the full scale range for measurements at the higher end of the range (example:

calibrating an Oxygen Purity Analyzer in air at 20.9% oxygen with the intention of measuring oxygen levels of 50-100%)

results in the effect of “expanding the error” by moving upscale as illustrated by Graph A and Example 1 in the Accuracy &

Calibration section above and is not recommended. Of course the user can always elect at his discretion to accept an

accuracy error of +

2-3% of full scale range if no other span gas is available.

Recommendations Air Calibration:

¾ Do not calibrate an analyzer employing the Pico-Ion UHP or MS sensor, or, an oxygen purity sensor with air.

¾ The inherent linearity of the galvanic fuel cell type oxygen sensor enables the user to calibrate any analyzer with ambient

air (20.9% oxygen) and operate the analyzer within the stated accuracy spec on the lowest most sensitive range available

with the analyzer – it is not necessary to recalibrate the analyzer with span gas containing a lower oxygen concentration.

¾ When installing or replacing a ppm or percent oxygen sensor.

¾ To verify the oxygen content of a certified span gas.

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 **).

Required components: Refer to Installing Span Gas section above.

Default Span

The software will eliminate any previous SPAN CALIBRATE adjustment(s) and display the actual the signal output of the sensor

at any specific oxygen concentration. This feature allows the user to assess the sensor’s signal output without removing it from

the sensor housing. For example, performing the DEFAULT SPAN feature followed by the introduction of a span gas, the display

will reflect an oxygen reading within +

50% of the span gas value. representing the sensor’s “actual” signal output and allows

the user to test the sensor’s signal output when exposed to a specific oxygen standard (without removing the sensor from the

sensor housing).

Procedure:

1. Access the MAIN MENU by pressing the MENU key.

2. Advance the reverse shade cursor using the ARROW keys to highlight CALIBRATION.

3. Press the ENTER key to select the highlighted menu option.

4. The following displays appears:

MAIN MENU

AUTO SAMPLE

MANUAL SAMPLE

CALIBRATION

>>>

CALIBRATION

SPAN CALIBRATE

ZERO CALIBRATE

DEFAULT SPAN

DEFAULT ZERO

OUTPUT SPAN

OUTPUT ZERO

5. Advance the reverse shade cursor using the ARROW keys to highlight DEFAULT SPAN.

6. Press the ENTER key to select the highlighted menu option.

7. The following displays appear and after 3 seconds the system returns to the SAMPLING mode:

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 34 35

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Analytical-industries GPR-1200 ATEX Portable Trace PPM Oxygen Analyzer Manuel d'utilisateur Page 20

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