Kestrel Relative Humidity Calibration Kit User Manual

Relative Humidity Calibration Kit

For calibrating the following Kestrel Meters

Model Numbers

3000, 3500, 4000, 4200, 4250, 4300, 4400, 4500, 4600

(Not to be used for calibrating Kestrel 5 Series units or Kestrel DROPs)

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©2017 Nielsen Kellerman Co. Kestrel, the Kestrel bird, NK, Nielsen-Kellerman and the
NK logo are registered trademarks of the Nielsen-Kellerman company.

Please refer to Standard Practice for maintaining Constant Relative Humidity by Means
of Aqueous Solutions ASTM Designation E104-85 (reapproved 1996) for additional
information.

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While the calibration process is simple, it is important that you follow the
steps carefully. A careless calibration could enter incorrect values into the
unit and degrade its performance.

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Factory Recalibration / Certication

The Kestrel should be recalibrated if the RH sensor has shown drift in its RH measurement. The Kestrel RH
sensor is specied 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 certication 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 certication.

Field Recalibration

As an alternative to Factory Recalibration, this kit allows you to perform dozens of humidity recalibrations in
the eld to ensure that your Kestrel is always performing within specications. 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 oce
and make sure your calibration location is not near any windows or air conditioning or heating vents. Even
temperature changes as slight as 2 deg F while calibrating can negatively impact accuracy so if you are
not sure that your calibration environment is stable enough, or to ensure an accurate calibration, place the
entire Cal Kit inside an insulated cooler or if a cooler is not available, wrapped 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).

Please read ALL of these instructions before

beginning the recalibration of your Kestrel!

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Contents of the Humidity Calibration Kit

» Two jars with color-coded salt chamber labels, plastic spacer grids and sealing lids
» One jar with no spacer grid (for water)
» One vial with magnesium chloride (MgCl) salt and blue color-coded label
» One vial with sodium chloride salt (NaCl)and red color-coded label
» One RH Calibration Kit insulated bag/carry case
» One color-coded labeled measuring cup

Note: Our calibration process has changed. The changes will require more time but will improve relative
humidity calibration accuracy vs. the previous method. Please familiarize yourself with the new process.
Note: Only place one Kestrel unit in each calibration jar at a time. Attempting to calibrate more than one
unit in each jar at the same time will reduce RH calibration accuracy. If you are attempting to calibrate
multiple units the process can be overlapped so that while the rst Kestrel unit is equilibrating in the

second jar, the second Kestrel unit can begin equilibrating in the rst jar.

Example Recalibration Schedule

Day 1 Day 2 Day 3

8:30am 9:00am 9:00am 10:00am 10:00am 11:00am

Set up
calibration
jars-30min

Begin
equilibration
in 1st jar-24hr

1st Jar
calibration
point taken-1hr

Begin
equilibration
in 2nd jar-24hr

2nd Jar
calibration point
taken-1hr

Complete