Delta-T Devices AP4, User Manual

Page: 24 / 64

CALIBRATION
Page 24
CALIBRATION SUMMARY
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Prepare calibration plate ahead of time.
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Leave it to stabilize, in its plastic envelope, for about 1 hour.
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Set RH close to ambient.
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Check other settings: -
Cup type: slotted or circular
Units: resistance or conductance
Pressure: actual barometric pressure
or average barometric pressure at your altitude or leave it at 1000 hPa (mbar)
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Insert damp calibration plate at position 1.
Ensure it fits snugly.
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Press GO to start the reading
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Wait until readings are stable, then press GO to ACCEPT it.
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Move plate to next position and repeat until all 6 positions are read.
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Select CURVE FIT.
The porometer then fits a calibration curve to the data, recalculates the results
and estimates the error.
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INSTALL if the error is less than 10%
Otherwise DISCARD and redo the worst result, or redo the whole calibration.
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Recalibrate when the temperature changes by more than 5°C.
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Recalibrate when changing RH set point.