The below definitions have been simplified in order to keep this section brief. We strongly
recommend that anyone who wishes to make use of these measurements refer to one of the
many excellent weather references available for a more in-depth definition. On the internet,
visit
www.usatoday.com or www.noaa.gov. Or, locate the USA Today publication, The Weather
Book. Please note that any words in a definition printed in italics are themselves defined in this
glossary.
Air Flow: The volume of air passing through an area for a given period of time. This is commonly
calculated by multiplying the air velocity by the cross sectional area through which the air is
passing.
Dewpoint: The temperature to which air must be cooled in order for condensation to occur. The
difference between dewpoint and temperature is referred to as the “temperature/dew point
spread”. A small dewpoint spread indicates high relative humidity, while a high dewpoint spread
indicates dry conditions.
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 our
ability to cool ourselves by evaporating perspiration is reduced.
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.
Temperature: The ambient air temperature.
Wind Chill: The cooling effect of combined wind and temperature. The wind chill gives a more
accurate reading of how cold it really feels to the human body. The Kestrel 4100’s wind chill is
based on the National Weather Service standards as of November 1, 2001.
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Stored data may be uploaded to a PC with the optional Kestrel PC Interface, NK part number 0830.
13
This section provides examples of applications where a Kestrel 4100 might be used, and the appropirate
memory settings.
HVAC - Environmental Monitoring
Auto Store On Store Rate 5min
Overwrite On Man Store Off
These settings will record conditions every five minutes, for a total storage of almost 21 hours. You can monitor
the conditions in a laboratory or manufacturing plant, both day and night, to determine if the climate control is
working properly. Or you can examine the effect on the environment when employees enter and exit the
building.
HVAC/R - System Function Verification
Auto Store Off Store Rate —
Overwrite Off Man Store On
These settings will require you to press the Manual Store Button in order to store any data at a duct, hood, vent,
or other system location. The meter will not store any data automatically. Be sure to record the location an date/
time of storage for reference when reviewing the data. After storing the conditions at each location, simply
review the data and balance the system.
Air Duct Measurements
There are two useful techniques for measuring air flow in a duct or at the face of a duct opening. First, the
unit can be used in the Max/Avg Mode(see page 8). Hold the unit in one corner or side of the duct. Press the
button to begin the averaging interval. Slowly traverse the duct. Press the button at the end of the
traverse of the duct. The maximum and average air flow measurements will be displayed.
Second, the unit can be used to store the air flow at multiple points in a duct. Hold the unit in one position
in or on the duct. Press the button to manually store the measurements (see page 9). Repeat this process
in multiple positions in or on the duct. When complete, review the stored measurements in the chart data
(see page 7), and average them if desired.
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UNIT METRIC IMPERIAL
Velocity m/s fpm
Air Flow m
3
/s fpm
Temperature Functions °C °F
Dimensions cm in
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 Screen1 velocity, air flow, temperature
User Screen 2 temperature, humidity, dewpoint
User Screen 3 air flow, temperature, humidity
Display Contrast 10
Automatic Shutdown 15 minutes
Language English
Store Rate Total Memory
2 sec 16 min
5 sec 40 min
10 sec 1 hr, 20 min
20 sec 2 hr, 40 min
30 sec 4 hr
1 min 8 hr
2 min 16 hr
5 min 1 day, 16 hr
Store Rate Total Memory
10 min 3 days, 8 hr
20 min 6 days, 16 hr
30 min 10 days
1 hr 20 days
2 hr 40 days
5 hr 100 days
12 hr 240 days
