Emerson 755A - Manual (Page 46)

Instruction Manual
245364-V
May 2002
3-14 Operation Rosemount Analytical Inc. A Division of Emerson Process Management
Model 755A
3-7 ROUTINE OPERATION
After the calibration procedure of Section 3-4
(page 3-4), admit sample gas to the analyzer
at the same pressure and the same flow rates
used for the zero and span gases. The
instrument will now continuously indicate the
oxygen content of the sample gas.
At this time, an adjustment of electronic
response time (R30 on the Control Board, see
Table 3-1, page 3-5, and Figure 3-2, page 3-
7), may be desirable to obtain the optimum
compromise between response speed and
noise.
3-8 EFFECT OF BAROMETRIC PRESSURE
CHANGES ON INSTRUMENT READOUT
If the analyzer exhaust port is vented through
a suitable absolute backpressure regulator,
and the installation site is at or near sea level,
barometric pressure changes do not affect the
percent oxygen readout. If conditions are
otherwise, the pressure compensation circuit
must be re-calibrated per Section 3-4d, page
3-8.
3-9 CALIBRATION FREQUENCY
The appropriate calibration interval will
depend on the accuracy required in the
particular application, and is best determined
by keeping a calibration log.