Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System - Manual (Page 48)

CPEC200 Closed-Path Eddy-Covariance System
Set valve_number to ZeroAir (1). If onsite, look at the LEDs on the valve
module to confirm the selected valve is now active. Verify valve_status
reports Valve flow is OK. If not, check the value of valve_flow and
troubleshoot as needed.
Verify cpec_status reports CPEC is OK. If not, troubleshoot as needed.
There is no automatic error checking in full manual mode, so
diagnostics must be checked manually.
Watch the values of CO
2
and H
2
O. When they stabilize, set DO_zero = True.
The IRGA will set its CO
2
and H
2
O readings to zero. Verify the values of H
2
O
and CO
2
are near zero.
Set valve_number = None (0) to stop the flow of zero gas.
6.3.2.3 Checking and Setting the CO
2
Span
The keyboard display has menus to facilitate manual zero control for users that
are onsite. Navigate:
Manual zero/span → Manual Control → CO2 Span
Set valve_number to one of the CO
2
span valves. If onsite, look at the LEDs
on the valve module to confirm the selected valve is now active. Verify
valve_status reports Valve flow is OK. If not, check the value of valve_flow
and troubleshoot as needed.
The 3-valve module has only one CO
2
span valve available,
CO2span1. The 6-valve module has three additional CO
2
span
valves available.
Make sure the value in CO2_SPAN_PPM matches the CO
2
concentration of
the CO
2
span cylinder you have selected.
Verify cpec_status reports CPEC is OK. If not, troubleshoot as needed.
There is no automatic error checking in full manual mode, so
diagnostics must be checked manually.
Watch the values of CO
2
and H
2
O. When they stabilize, set DO_CO2_span =
True. The IRGA will set the CO
2
span to the value in CO2_SPAN_PPM.
Verify the measured value CO2 now matches the value of CO2_SPAN_PPM.
Set valve_number = None (0) to stop the flow of CO
2
span gas.
6.3.2.4 Checking and Setting the H
2
O Span
H
2
O is more difficult to span than CO
2
because it is more difficult to provide a
source of air with known humidity. In most cases, a commercially available
dewpoint generator is used.
NOTE
NOTE
NOTE
38