Campbell Scientific IRGASON Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer - Manual (Page 28)

IRGASON ® Integrated CO
2
/H
2
O Open-Path Gas Analyzer and 3D Sonic Anemometer
7.11 Pressure Sensor
This setting identifies which barometric pressure sensor is used. The EC100
always includes the basic barometer, but it may be ordered with the optional
enhanced barometer (model CS106). This setting defaults to EC100
Enhanced if the CS106 is ordered and to EC100 Basic otherwise.
There are two other possible settings for Pressure Sensor. First, the user may
supply a different pressure sensor. In this case, the setting should be changed
to User Supplied, with the appropriate values for gain and offset entered (see
below).
The final option is to select None for Pressure Sensor. The EC100 will use a
fixed (see below) value for pressure. This mode is intended for
troubleshooting only.
7.11.1 Pressure Gain
If Pressure Sensor is set to User Supplied, this setting gives the gain factor
(kPa/V) used to convert measured voltage to pressure. Normally, Pressure
Sensor is set to EC100 Basic or EC100 Enhanced, and this setting is not
used.
7.11.2 Pressure Offset
If Pressure Sensor is set to User Supplied, this setting gives the offset (kPa)
used to convert measured voltage to pressure. Normally, Pressure Sensor is
set to EC100 Basic or EC100 Enhanced, and this setting is not used.
7.11.3 Fixed Pressure Value
If Pressure Sensor is None, the EC100 will use the value of this setting for the
barometric pressure. This mode is intended for troubleshooting only. In
normal operation, this setting is not used.
7.12 Pressure Differential Enable
This setting should remain disabled. It is used only for closed-path analyzers.
7.13 Heater Control
An advantage of the IRGASON’s low power consumption (5W) is that the
instrument remains at a temperature very close to ambient air temperature,
which is an important feature for eddy-covariance measurements. Under some
environmental conditions, however, the analyzer can become colder than
ambient air temperature which may increase the likelihood of frost or
condensation building on the optical windows. This will affect signal strength.
The IRGASON design includes internal heaters located at the optical windows,
which aid in minimizing data loss during these specific environmental
conditions.
An automatic heater control algorithm can be activated from either Device
Configuration or ECMon by putting in a value of −2, or deactivated by putting
in a value of −1. 7
7 Automatic heater control is available in EC100 OS version 4.07 or greater and is turned on by
default starting with the OPEC program version 3.2.
18