Kestrel
®
4300 Construction Weather Tracker
Heat Index
A practical measure of how hot the current combination of
relative humidity
and
temperature
feels to a
human body. Higher
relative humidity
makes it seem hotter because the body’s ability to cool itself by
evaporating perspiration is reduced.
Reference Pressure
The local
barometric pressure
. Input to the
altitude
screen to provide correct altitude readings. Also known
as the
altimeter setting
.
Relative Humidity
The amount of water vapor actually in the air divided by the maximum amount of water vapor the air could
hold at that
temperature
, expressed as a percentage.
Station Pressure
The
air pressure
of your location, NOT reduced to the sea level equivalent.
Temperature
The ambient air temperature.
Wet Bulb Temperature
The lowest
temperature
to which a thermometer can be cooled by evaporating water into the air at constant
pressure. This measurement is a holdover from the use of an instrument called a sling psychrometer. To
measure wet bulb temperature with a sling psychrometer, a thermometer with a wet cloth covering over
the bulb is spun rapidly through the air. If the relative humidity is high, there will be little evaporative
cooling and the wet bulb temperature will be quite close to the ambient temperature. Some exercise
physiology guides use
wet bulb temperature
, rather than
heat index,
as a measure of the safety of exercise in
hot and humid conditions.
Wind Chill
The cooling eff ect of combining wind and temperature. The wind chill gives a more accurate reading of
how cold it really feels to the human body. The Kestrel Meter’s wind chill is based on the National Weather
Service standards as of November 1, 2001.
27
DEFAULT SETTINGS
UNIT
METRIC
IMPERIAL
Wind Functions
M/s
mph
Temperature Functions
°C
°F
Barometric Pressure
hPa
inHg
Altitude Functions
M
Ft
Time Format
24 hour
12 hour
Date Format
Day/month/year
Month/day/year
SETTING
FACTORY DEFAULT
Automatic Data Store
On
Data Store Rate
1 hour
Data Overwrite
On
Manual Data Store
On
User Screen 1
Wind speed, temperature, humidity
User Screen 2
Humidity, dewpoint, wet bulb
User Screen 3
Pressure, altitude, density altitude
Display Contrast
10
Automatic Shutdown
15 minutes
Language
English
PC Upload
Stored data may be uploaded to a PC with the optional Kestrel Interface.
Kestrel
®
4300 Construction Weather Tracker
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
suffi cient 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.”
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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 fi rmly
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 airfl ow 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), airfl ow over the sensors is necessary to measure
accurate temperature and humidity readings. You can ensure airfl ow by either placing the Kestrel Meter in
a breeze, or by waving it back and forth. If no airfl ow 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 diff erent 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
