Kestrel 4300 (Construction) - Manual (Page 6)

Kestrel ® 4300 Construction Weather Tracker 11
While viewing the Min/Max/Avg screen for any of these measurements, hold the unit into the wind, and
press the button when the screen displays “--average” to begin collecting data for all measurements, and
again when the screen displays “--stop” to stop collecting data and hold the values on the display. Press the
button when the screen displays “--clear” to clear the data. This routine will work simultaneously for all
measurements, regardless of which one is displayed while the routine is run. The Max/Avg for these wind
values will not affect any other Min/Max/Avg or stored data.
Manual Data Storage
To manually store data, press the button. One of the following will appear: Data Stored (data has been
captured and will appear on chart), Full (Overwrite is off and data log is full), or Off (Manual Store button
has been disabled). (See the Main Setup Menu section for more information on memory.)
Backlight
The Kestrel Meter has a high-visibility green backlight, which makes the display easily read in low–light
conditions. Press the button to activate the backlight. The light will remain activated for one minute.
Press the button within one minute to deactivate the light manually.
Relative Humidity
The Kestrel Meter is capable of measuring RH to a high accuracy: +/– 3% RH between 5 and 95%. To ensure
operation within these specifications, please follow these recommendations:
• Avoid taking measurements in direct sunlight, which will heat the air inside the humidity sensor
enclosure and cause inaccurate readings.
• If your circumstances force you to expose the Kestrel Meter to a large temperature swing prior to taking
a relative humidity reading (such as when taking a Kestrel Meter stored inside at 70° F outside to a
temperature of 40° F), you will need to take additional steps to ensure that the Kestrel Meter’s external
temperature sensor is in thermal equilibrium.
- Ideally, provide an airflow of at least 1 M/S (2.2 MPH), over the temperature sensor—point the
Kestrel Meter into the airflow. If there is no airflow, simply wave the unit back and forth so air
passes over the sensors. With airflow over the temperature sensors and humidity chambers,
readings within specifications will be provided within two to three minutes, even after a large
temperature shift.
- If no airflow can be provided, you must allow sufficient time for the RH value to stabilize. This can
take as long as 20 minutes—the greater the temperature change, the greater the time. You can
use the logging capability of the Kestrel Meter to confirm that the unit has stabilized to
a correct reading: Set the memory options to a relatively short logging interval (20 seconds
works well), select the graphical display of RH, and you can see when the value is no longer
changing significantly. At that point, the RH value is stable and can be relied upon to be within the
accuracy specifications.
Barometric Pressure and Altitude Adjustment
The Kestrel Meter measures station pressure—the actual air pressure in the measurement location—and
uses this value to calculate barometric pressure and altitude. Station pressure changes in response to
two things—changes in altitude and changes in the atmosphere. Because the Kestrel Meter is constantly
changing location and altitude, it is important to enter adjustments or “references” when accurate pressure
and altitude readings are needed.
Barometric pressure is station pressure corrected to sea level. In order to make the correction, the Kestrel
Meter needs an accurate reference altitude. Altitude is the height above sea level. In order to correctly
calculate altitude, the unit needs an accurate barometric pressure reference, also known as an “altimeter
setting”. You only need to know ONE of these values (current barometric pressure or current altitude) in
order to set your Kestrel Meter up to show accurate readings.