3-40 | IPS-4 Dual Bench (UV / IR) Analyzer
Adjusting the Zero/Span Fluid Flow Rate
When the zero or span (if used) flow solenoid is in an energized state,
Instrument Air (or Nitrogen or distilled water) flows into the sample
path via a solenoid manifold block and a flow meter. The flow rate of
Zero/Span (if used) fluid must be high enough to adequately flush the
Measuring Cell of sample fluid to obtain a “good zero.”
Typically, the IPS-4 Analyzer controls the zero (and span, if used)
flow rate; no adjustments are required.
If the customer provides the sample system zero, run the manual zero
at a flow rate of 2.5 L/minute (0.08 scfm). Since excess air flow into
the analyzer sample system will cool the Measuring Cell and Oven/
Sample System Enclosure, the optimum Zero fluid flow rate is the
lowest consistent with a good zero.
A good zero can be defined as a state where the concentration outputs
are stable and further increases in Zero fluid flow rate do not reduce the
concentrations observed on the analyzer User Interface Panel. A mid-scale
flow indicator (or meter) should be sufficient for this purpose.
While the sample system is warming up, or when the analyzer is in
standby mode (Not Ready state), zero flow may be desired. During these
conditions, it is important that the sample system is kept free of contami-
nation by the sample fluid.
For additional information, refer to the Sample System Manual Supplement
in the “Supplemental Information” section of this manual or in the
Documentation Package shipped with the analyzer.
NOTE
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