Product Manual
3
Factory Recalibration / Certication
The Kestrel should be recalibrated if the RH sensor has shown drift in its RH measurement. The Kestrel RH
sensor is specied to develop less than 2% drift over 24 months. You may return your Kestrel to NK for Factory
Recalibration of the relative humidity and related measurements. Recalibration is available with and without
certication of NIST traceability and calibration stickers. Note that NK can recalibrate and certify any of the
values measured by your Kestrel. Please contact NK for more information about Factory Recalibration and
certication.
RH Factory calibration of Kestrel 5 Series units will return units to within +/-2% accuracy spec.
RH Factory calibration of Kestrel 3000-3500 & 4 Series units will return units to within +/-3% accuracy spec.
Field Recalibration
As an alternative to Factory Recalibration, this kit allows you to perform dozens of humidity recalibrations in
the eld to improve sensor accuracy and address the eects of RH drift. This manual explains in detail all of the
steps for recalibrating your Kestrel’s humidity Sensor. This process will take approximately 50 hours, including
setup and calibration. Ensure that you are performing the calibration in a climate controlled environment such
as a home or oce and make sure your calibration location is not near any windows or air conditioning or heat-
ing vents. Even temperature uctuations as slight as 2 deg F while calibrating can negatively impact accuracy,
so if you are not sure that your calibration environment is stable, place the entire Cal Kit inside an insulated
cooler or if a cooler is not available, wrap it in a thick blanket. Further temperature control can be gained by
placing additional containers of room temperature water inside the cooler or blanket, (gallon jugs work ne).
RH Field calibration of Kestrel 5 Series, 4 Series and 3000-3500 Series units will typically return units to
within +/-3% accuracy but actual results can vary depending on the user’s ability to control the calibration
environment.
Please read the complete instructions for your unit before
beginning the recalibration of your Kestrel