Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System - Manual (Page 43)

CPEC200 Closed-Path Eddy-Covariance System
Public variable mode_status describes the basic operating state of the
CPEC200. Verify mode_status = Normal EC mode. See Appendix A,
CPEC200 Diagnostics, for further information.
Public variable cpec_status gives an overall status for the entire system. If
there are no problems detected, cpec_status will report CPEC is OK. See
Appendix A, CPEC200 Diagnostics, for further information.
If the CPEC200 was not configured with the optional valve module, the
installation is now complete. If the valve module is installed, use the zero/span
capability of the CPEC200 as described in Section 6, Zero and Span.
6. Zero and Span
6.1 Introduction
The EC155 must be zeroed and spanned periodically to maintain its accuracy.
This requires the user to supply cylinders of zero air and CO
2
span gas and
appropriate regulators.
Use high-quality gases for the zero and CO
2
span. The zero gas
must be free of significant water vapor and CO
2
. The CO
2
span
gas should have a well-known concentration of CO
2
, balanced in
air (not nitrogen).
There are three ways that the EC155 can be zeroed and spanned:
1. The EC155 can be zeroed and spanned independently of the CPEC200
system, per the instructions in the EC155 CO
2
and H
2
O Closed-Path
Gas Analyzer Manual. This option can zero and span both CO
2
and
H
2
O. This is the only choice if the CPEC200 was configured without
the optional valve module.
2. The EC155 zero and CO
2
span may be performed automatically by the
CPEC200 system. This requires the CPEC200 be configured with the
optional valve module. This method can zero both CO
2
and H
2
O but
can span only CO
2
. Further details for this option are given in Section
6.2, Automatic Zero and Span.
3. The optional valve module allows the EC155 zero and span to be
performed manually at the field site. If the CPEC200 has been
configured with an internet connection, the manual zero and span may
also be done remotely. Although CO
2
and H
2
O zero, and CO
2
span
may be performed remotely, H
2
O span requires the dewpoint
generator to be brought to the field site. Further details for this option
are given in Section 6.3, Manual Zero and Span.
See Section 5.2.2, Zero
/
Span, for details on plumbing connections to zero and
span the EC155 while installed in the CPEC200. The following sections give
details on configuring the CPEC200 for either automatic or manual zero and
span.
NOTE
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