Campbell Scientific TGA100 Trace Gas Analyzer Manual - Manual (Page 97)

0
5
10
15
20
25
30
0 10 20 30 40 50 60 70 80
Pressure (mbar)
Flow Rate (slpm)
60 Hz
50 Hz
Figure 9-1. RB0021 Sample Pump Flow Rate
9.4 Sample Air Dryers
Accurate measurements of trace gas fluxes by eddy covariance or gradient techniques require that variation in water
vapor concentration be eliminated either by drying the sample gas before it is measured or by correcting the trace gas
flux (Webb, E.K., Pearman, G.I. and Leuning, R.: 1980, "Correction of flux measurements for density effects due to
heat and water vapor transfer", Quart. J. Met. Soc. 106: 85-100). Two sample air dryers are designed for use with the
TGA100, the PD1000 and the PD625. The PD1000 is recommended high flow applications, and the PD625 is
recommended for low flow applications.
9.4.1 General Description
The PD1000 consists of a 200-tube, 48" Nafion® dryer element manufactured by Perma Pure, Inc., that is housed in a
rugged dryer shell designed and manufactured by Campbell Scientific. The PD1000 includes a filter holder and spare
filter membranes, flow meters to measure the sample flow and purge flow, needle valves to adjust the flow rates and
pressures, and mounting hardware. The various parts of the PD1000 are illustrated below.
Mounting Bracket
Sample Inlet
Filter Holder
Purge Outlet Purge Flowmeter
Purge Needle Valve
Sample Needle Valve
Sample Outlet
Figure 9-2. PD1000 High Flow Sample Air Dryer
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