Teledyne API Model 200A NOX Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
Table 6-6-1: Zero/Span Valve Operation
Mode Description Reference Section
1. Front panel operation via
CALS and CALZ buttons
Calibration Section 7 - Manual Zero/Span Check.
2. Automatic operation using
AUTOCAL
Setup and use of AUTOCAL is described in Table 6-2,
and Section 7.4.
3. Remote operation using the
RS-232 interface
Setup described in Table 6-2. Operation of AUTOCAL
described in Section 5.5 and Section 7 - Calibration. A
complete description of the RS-232 interface is available.
Order part number 01530.
4. Remote operation using
external contact closures
Section 7.7 - Automatic operation using external contact
closures. Truth Table 7-9 and Section 9.3.4.3.
The Zero/Span valves have 3 operational states:
1. Sample mode. Here both valves are de-energized and sample gas passes through the
sample/cal valve and into the analyzer.
2. Zero mode. The sample/cal valve is energized to the cal mode. The zero/span valve is de-
energized in the zero mode, thus allowing zero gas to be admitted through the rear panel
bulkhead fitting into the analyzer.
3. Span mode. The sample/cal valve is energized and in the cal mode. The zero/span valve
is energized in the span mode. With both valves on, span gas is admitted through a rear panel
bulkhead fitting into the analyzer.
Zero air and span gas inlets should supply their respective gases in excess of the 500 cc/min
demand of the Analyzer. Supply and vent lines should be of sufficient length and diameter to
prevent back diffusion and pressure effects. See Table 2-2-3 for fitting location and tubing
recommendations.
Adequate zero air can be supplied by connecting a Purafil/charcoal scrubber and 5 micron
particulate filter (Teledyne API P/N 000369) to the zero air inlet tubing. The zero air scrubber
used in conjunction with the Zero/Span Valve option provides an inexpensive source of zero air.
Another source of zero air is the Model 701 zero air generator.
6-2
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