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FIGURE 8-3. Exploded view of CSAT3BH desiccant canister
8.4 Calibration
The CSAT3BH is calibrated at the factory over the temperature range of –40 to 50 °C, as sonic
transducer response is a function of temperature. Any measurements taken at temperatures
outside of this range will be suspect.
The CSAT3BH does not require field calibration; however, it may require a factory recalibration
every few years. An indication that the CSAT3BH is due to be returned to the factory for
recalibration is when diagnostic flags are persistent under dry conditions with little to no wind
and with no obstruction in the ultrasonic paths. A wind offset greater than the specifications
found in
(p. 17) is another indication that a recalibration is due. To check for wind
offset, refer to
8.4.1 Test for wind offset
Testing wind offset on a CSAT3BH requires creating an environment where wind is absent.
Because it is difficult to do this in the field, wind offset data from the CSAT3BH should be
collected in a field office or the lab. A zero-wind environment can be created with a kitchen waste
bin liner. The following steps should be taken to test the CSAT3BH for wind offset.
1. Mount the head using the horizontal mount boom (as described in
(p. 31)), or
hang the head from the block that supports the CSAT3BH upper and lower arms. Do not
CSAT3BH Three-Dimensional Heated Sonic Anemometer
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