Campbell Scientific AP200 CO2/H2O Atmospheric Profile System - Manual (Page 25)

AP200 CO
2
/H
2
O Atmospheric Profile System
4.2.1 Intake Assemblies
The AP200 intake assembly (pn 27693) includes a heated rain diverter, an
inline filter, an orifice, and a mixing volume on a common mounting bracket
with rain cover, shown opened in FIGURE 4-18. The inline filter element, pn
29998, is a 2.5-cm (1.0-in) diameter, PTFE membrane with a 3-micron pore
size. It removes particulates from the air sample that could clog the orifice or
valve.
FIGURE 4-18. AP200 intake assembly shown open
The orifice has a diameter of 0.18 mm (0.007 in) to restrict flow to a
maximum of approximately 247 standard ml•min -1 at sea level. The flow will
be reduced at higher elevations due to the lower atmospheric pressure. The
nominal ambient pressure as a function of elevation is shown in FIGURE 4-19.
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