Kestrel 4300 (Construction) - Manual (Page 5)

Kestrel ® 4300 Construction Weather Tracker 9
SPECIAL FUNCTIONS
Evaporation Rate
The Kestrel 4300 will display the evaporation rate, based on the instantaneous air velocity, relative humidity,
ambient temperature and concrete temperature. The 4300 eliminates the need to reference the American
Concrete Institute issued charts.
To measure the evaporation rate, you will need to input the concrete temperature. The Kestrel 4300 does
not measure this, you will need to use a separate temperature measuring device to obtain the concrete
temperature.
Once you have measured the concrete temperature, scroll to the evaporation rate screen, then press
the button. Now you can use the and buttons to enter the concrete temperature. Press
the button again to exit the setting screen.
To accurately measure the evaporation rate, a few precautions must be taken. The readings must be taken
into the wind, approximately 20 inches above the concrete. Additionally, it is extremely important that the
temperature reading is not taken in direct sunlight. You may need to shade the Kestrel Meter if the area is
not normally in the shade. For example, hold a notebook or piece of plywood above the Kestrel so that it is
shaded while taking the readings. (Be careful not to obstruct the air flow while doing so.) Failure to shade
the unit may cause inaccurate Evaporation Rate readings, and will not meet the criteria in the ACI
308.
Find the direction that the wind is blowing from and hold the Kestrel 4300 into the wind. You may want
to scroll up to the Current Wind Speed Screen to find the direction that the wind is strongest. Hold the
unit vertical, and rotate it slightly to find the maximum wind speed. Then scroll back to the evaporation
rate screen and hold the Kestrel 4300 facing that direction. The Kestrel 4300 will automatically display the
instantaneous evaporation rate.
Since the wind rarely blows at a constant rate, you may notice that the evaporation rate fluctuates. For the
most accurate evaporation rate readings, press the button to enter the averaging screen. This allows
you to average the evaporation rate over a set time. The ACI recommends averaging for 6-10 seconds. On
the average screen, press the button to start the averaging. Position the Kestrel into the wind, 20 inches
above the concrete and shaded, and count 6-10 seconds, then press the – button again to stop. The screen
will display the average and minimum evaporation rate readings. To clear the data, press the – button
again. Press the < button to return to the current evaporation rate screen, or the > button to view the
chart.
Note that you may change the units of measure for Evaporation Rate under the Main Setup Menu (see the
Main Menu setup section instructions). Choices are lb/ft 2 /hr and kg/m 2 /hr.
User Screens
The Kestrel Meter has three User Screens that can be customized to display three
current measurements simultaneously. These screens can also be turned off. (See the
Main Menu section for setup instructions.)
Max/Avg for Wind Speed & Wind Chill
The Max/Avg values for the wind speed and wind chill values are measured independently from the stored
and charted data.
This allows the user to start and stop the averaging period in the most appropriate manner for their
application. Averaging on all wind-related values (Wind Speed and Wind Chill) will be started and
stopped together.