Rosemount 755A, Инструкция по эксплуатации

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I
NITIAL
S
TARTUP AND
C
ALIBRATION
3-10
April 2000 Rosemount Analytical 245364-U Model 755A Oxygen Analyzer
S
TANDARD
P
ROCEDURE
: C
ALIBRATION BY
P
RESSURE
D
ECREASE
1. Verify that the Pressure Compensation Option is selected, i.e., Jumper inserted
between E1 and E3 on the Control Board.
2. Connect a compound range pressure gauge (or mercury manometer), pressure
gauge, pressure regulator, flowmeter, needle valves and vacuum pump as shown
in Figure 3-3.
3. Open V2, set PR1 to approximately 10 psig (69 kPa) and adjust V1 for a flow rate
of 250 cc/min. into the sample inlet line. Compound range pressure gauge (or
mercury manometer) should indicate close to atmospheric pressure (0.00).
4. Set TEST switch to PRESS CAL 1 and adjust CAL 1 potentiometer R98 (see Table
3-1, Figure 3-2) for a reading of 00.00
±
5 counts on the display.
5. Set TEST switch to NORM and note display reading.
6. Start vacuum pump.
7. Close V2 and adjust V3 and V4 to decrease the pressure on the sample exhaust
by about 3%. (-12.00 inches of water; -0.4 psi; -23 mm of mercury; -3 kPa).
8. Adjust CAL 2 potentiometer R99 (see Table 3-1, Figure 3-2) until reading on
display is the same noted in step 5.
9. Repeat steps 3 through 7 as many times as necessary to ensure repeatability of
compensation calibration.
Note
Although not mandatory, it is desirable, in order to obtain maximum accuracy,
that the oxygen concentration of the gas used during calibration be close to that
of the process stream which is to be analyzed.
3.4 COMPENSATION FOR COMPOSITION OF BACKGROUND GAS
Any gas having a compensation 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 cab 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),
however, background effects must be taken into consideration to ensure correct
readout.
During adjustment of the ZERO and SPAN controls (on the analyzer door), the
instrument is set to indicate, not the true oxygen content of the downscale and