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B-1
Appendix B. Sampling Site, Regime,
and Mode
Sampling sites, regimes, and modes are applicable to the CPEC310 and help
distinguish certain states of the system. A sampling site refers to a particular
valve selection or air sampling source. TABLE
defined sampling sites.
A sampling regime consists of a site designation, a state of the pump (on or
off), and an omit status, which is whether or not the current measurements are
being included in calculations and statistics. For example, the steps in the auto
zero/span sequence in TABLE
each describe a sampling regime. The
sampling regime at a given moment is described by the variable
sampling_regime,
which is included in the Time_Series output table, where
bits 0 through 3 correspond to the site number, and bit 4 is set when
measurements are being omitted from calculations. For example, if the system
has just finished an auto zero and span cycle and has returned to normal EC
measurements (site 1), it will omit measurements from the covariance and
other calculations for 25 seconds in order for the sample cell to be thoroughly
flushed and the pressure equilibrated; during this 25 second time period,
sampling_regime
will have a value of 17, where the fourth bit is set high
(decimal value of 16) to indicate omitted measurements, and bit zero is set to 1
(decimal value of 1), corresponding to site 1. After the 25 second period has
passed,
sampling_regime
will show a value of 1, indicating the measurements
are no longer omitted and the current site is Site 1.
A sampling mode, or simply mode, is a timed or controlled sequence of one or
more sampling regimes. TABLE
below lists the various modes. For
example, in the case of Auto Z/S mode, a sequence of several sampling
regimes is completed in order to perform a zero and span of the gas analyzer.
TABLE B-1. Site Numbers, Text Descriptors, and Descriptions
Site
Number
Text Descriptor of
Site (used on
CR1000KD display)
Description
1
fld smp
Normal field sampling. The pump is
on and pulling ambient air into the
sample cell.
2
offst P
The pump is off. This setting is used to
measure the offset between the sample
cell pressure sensor and the EC100
barometer.
3
chk CO2
Check CO
2
span
4
chk zro
Check Zero
5
set zro
Set Zero
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