Rosemount 755, Инструкция по эксплуатации

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M
ODEL
755 O
XYGEN
A
NALYZER
3-6
748183-H Rosemount Analytical
November 1997
EXAMPLE
Range, 90% to 100% oxygen
Upscale Standard Gas, 99.7% oxygen
8. Set % RANGE Switch for 90% to 100% oxygen. Then adjust SPAN Control for
recorder reading of 99.7% oxygen. Return % RANGE Switch to 99% to 100%
range.
9. Repeat Steps 4b and 5 as many times as necessary until recorder reads 99.7%
oxygen regardless of position of % RANGE Switch.
10. Admit a gas containing a known concentration of oxygen in the range of 90% to
100% oxygen. Verify that the recorder indicates the correct value.
11. Pass upscale standard gas through analyzer at 250 cc/min. Allow gas to purge
analyzer for minimum of 3 minutes.
12. Obtain recorder reading of 99.7% oxygen, by adjustment of (a) R45 and, if
necessary, (b) ZERO Control.
3.3 COMPENSATION FOR COMPOSITION OF BACKGROUND
GAS
Any gas having a composition other than 100% oxygen contains background gas. The
background gas comprises all non-oxygen constituents. Although instrument response
to most gases other than oxygen is comparatively slight, it is not in all cases negligible.
Contribution of these components to instrument response is a function of the span and
range used, and can be computed for each individual case.
If the downscale and upscale standard gases contain the same background gas as the
sample, the routine standardization procedure automatically compensates for the
background components: therefore, they introduce no error.
If the background gas in the sample is different from that in the downscale and/or
upscale standard gas(es) background effects must be taken into consideration to
ensure correct readout. During adjustment of the front-panel ZERO and SPAN
Controls, the instrument is set to indicate not the true oxygen content of the downscale
and upscale standard gases, but slightly different values, calculated to provide correct
readout during subsequent analysis of the sample gas. The calculations are explained
in Section 3.3.2.