Teledyne 9110TH - Nitrogen Oxides Analyzer - Manual (Page 54)

Model 9110TH NOx Analyzer Getting Started
Teledyne Analytical Instruments 34
All supply lines should be vented outside of the analyzer’s enclosure. In order to
prevent back-diffusion and pressure drop effects, these vent lines should be between 2
and 10 meters in length.
3.5.3.2. Zero Scrubber/Dual Pressurized Span Valve (OPT 50D)
The zero air scrubber of Option 50D is a cartridge, which is used to produce and supply
zero air to the analyzer’s ZERO inlet port. The cartridge mounts to the outside rear panel
and contains two chemicals: 50% volume of Purafil Chemisorbant to convert NO to
NO
2
, followed by 50% volume of charcoal to absorb NO
2
.
The dual pressurized span valves of Option 50D are a special set of valves that allows
two separate NO
x
mixtures to enter the analyzer from two independent sources.
Typically these two gas mixtures will come from two, separate, pressurized bottles of
certified calibration gas: one mixed to produce a NO, NO
2
or NO
x
concentration equal
to the expected span calibration value for the application and the other mixed to produce
a concentration at or near the midpoint of the intended measurement range. Individual
gas inlets, labeled HIGH SPAN and LOW SPAN are provided at the back on the
analyzer.
The valves allow the user to switch between the two sources via the front panel touch
screen control buttons or from a remote location by way of either the analyzer’s digital
control inputs or by sending commands over its serial I/O port(s).
Note The analyzer’s software only allows the SLOPE and OFFSET to be
calculated when sample is being routed through the HIGH SPAN inlet.
The LOW SPAN gas is for midpoint reference checks only.
The state of the optional valves can be controlled:
 Manually from the analyzer’s front panel by using the SIGNAL I/O
submenu located under the DIAG menu (Section 4.13.2),
 By activating the instrument’s CAL or AutoCal features (Section 5.8),
 Remotely by using the external digital control inputs (Section 4.15.1.2) or
Ethernet.
 Remotely through the RS-232/485 serial I/O ports (Section 4.11).