Kestrel 4300 (Construction) - Manual (Page 15)

Kestrel ® 4300 Construction Weather Tracker 29
FREQUENTLY ASKED QUESTIONS
How can a Kestrel 4300 help prevent plastic shrinkage cracks?
Plastic shrinkage cracks occur when the surface of the concrete dries rapidly and shrinks before it can gain
sufficient tensile strength to resist cracking. When ambient conditions and concrete temperatures combine
to produce conditions that create a high evaporation rate, the chances of the surface drying prematurely
and shrinkage cracks forming increases. Although most people associate high evaporation rates with hot,
dry weather, it’s important to note that placing hot concrete on a cold, dry day can actually create a much
worse condition. A Kestrel 4300 measures the ambient temperature, wind speed and relative humidity with
great accuracy. With the manual input of the concrete temperature, it can calculate the evaporation rate
which can help determine how prone the job is to plastic shrinkage cracks. Evaporation rate can also be
determined from the ACI 308 charts, though the Kestrel Meter provides a more accurate, convenient way to
take the measurement.
How do I set my Kestrel Meter to read the correct barometric pressure and altitude?
To measure these values accurately, you must know either your current pressure or altitude. If you know
the current barometric pressure, go to the altitude screen, and press the – button to enter the reference
pressure. As you adjust the reference pressure, you will notice that the altitude will change. Once the
reference pressure is entered, note the new altitude, and go to the barometric pressure screen. Press the
– button to enter this altitude as the reference altitude. Your Kestrel Meter is now displaying the accurate
pressure and altitude. (If you start with a known altitude, simply start with entering this value as the
reference altitude on the barometric pressure screen. The adjust the reference barometric pressure on the
altitude screen.)
You will need to update the reference pressure and altitude as you change altitude or the weather changes.
For more information on this topic, see the Barometric Pressure and Altitude Adjustment section under
“Special Functions.”
Why is my Kestrel Meter is not registering wind speed?
It probably just needs a replacement impeller. You can verify this by removing the impeller (press firmly
on the sides of the impeller), and turn the unit on to the wind speed screen. Hold the Kestrel Meter near a
television, computer monitor or some electronic device and it will display a wind speed. Or, wave a magnet
(like a refrigerator magnet) back and forth by the Kestrel Meter. If the Kestrel Meter is working properly,
you will register a wind speed reading, even though there is no impeller installed. Simply purchase a new
impeller and your Kestrel Meter’s wind speed readings will be restored to factory calibration.
What is the best way to take accurate temperature and humidity readings?
Avoid taking measurements in direct sunlight, and be sure there is airflow over the sensors. Especially if you
expose the Kestrel Meter to a large temperature swing prior to taking a reading (such as taking a Kestrel
Meter from the indoors to the outdoors in the winter), airflow over the sensors is necessary to measure
accurate temperature and humidity readings. You can ensure airflow by either placing the Kestrel Meter in
a breeze, or by waving it back and forth. If no airflow can be provided, you must allow up to 20 minutes for
the values to stabilize and accurate readings to be displayed.
Can my Kestrel Meter measure water speed by placing it in wind speed mode and submerging it?
Even though your Kestrel Meter is fully waterproof and can be submerged without damage, the viscosity
of water is different than that of air. The Kestrel Meter will display a value, but the readings will not be the
accurate water speed.
Why does my screen turn black in the heat? Why does screen become sluggish or blank in the cold?
The liquid crystal display used in Kestrel Meters has an operational temperature range of -49.0 to 257.0°F
(-45.0 to 125.0°C). Above this temperature, the whole screen will turn black. Below this temperature, the