Campbell Scientific AP200 CO2/H2O Atmospheric Profile System - Manual (Page 38)

AP200 CO
2
/H
2
O Atmospheric Profile System
FIGURE 5-8. AP200 system enclosure configured with cylinders of
zero air and CO
2
Flow meters and needle valves are not needed because the
AP200 zero and span inlets have flow restriction inside the
system enclosure to set the flow rate.
Make sure there are no leaks in the regulators or the connections
to the valve module. For automatic operation, the tank shutoff
valves are left continuously open. A plumbing leak could cause
the contents of the tank to be lost.
When inlets are not in use, replace the Swagelok ® plug to keep
the system clean.
Open the shut-off valves on the cylinders and set the pressure regulators for 0-
psig delivery pressure.
If the pressure is inadvertently adjusted to high, the tube fitting
may need to be slightly loosened to bleed off the excess pressure.
Retighten the fitting when the proper setting is reached.
5.2.3 H
2
O Span
The H
2
O span can be performed only as a manual operation. Automated H
2
O
span is not feasible because it would require a dewpoint generator to provide
the H
2
O span gas all the time. The H
2
O span inlet is not bypass equipped, so it
will flow only when selected. This inlet can be connected to the output of a
dewpoint generator using a tee at the inlet, as shown in FIGURE 5-9, to bleed
off excess flow and avoid pressurizing the dewpoint generator.
NOTE
NOTE
26