Extech Instruments AN320 User Manual page 7

Relative Humidity, Wet Bulb/Dew Point Temperature, and CO
Sensors are built in to the center of the vane (rear of meter) and are used to measure relative
humidity, air temperature, and CO
on temperature and humidity readings.
1. Press U/mode to scroll to RH (%) or CO
carbon dioxide readings will be displayed on the upper LCD digits as selected.
2. Use the L/mode button to scroll through air temperature, dew point temperature, wet bulb
temperature, and air flow (volume) readings.
3. To measure the humidity using an offset reference value, please access the Setup mode and
input the offset value as described in the Setup mode section. The LCD will display the
measured value minus the offset value once the offset is programmed in the Setup mode.
Data Hold Mode
1. Press the HOLD button from the normal operating mode to freeze the current measurement.
2. The 'HOLD' icon will appear at the top of the LCD display.
3. Press HOLD again to return to normal operation. The 'HOLD' icon will switch OFF and the
meter will return to displaying readings in real time.
MAX/MIN Mode
The MAX‐MIN feature records the highest (MAX) and lowest (MIN) readings captured since the
MAX‐MIN mode was accessed.
1. Press and hold the MAX/MIN button for 2 seconds to begin displaying the lowest (minimum)
readings encountered since this mode was accessed. The 'MIN' icon will appear at the top of
the LCD display indicating that the readings shown are the lowest measured.
2. Press and hold the MAX/MIN button again for 2 seconds to display the maximum readings
encountered. The 'MAX' icon will appear on the LCD.
3. Press and hold this button again for 2 seconds to return to the normal mode of operation
(the 'MIN' and 'MAX' icons should switch OFF).
4. While viewing the MAX or MIN data, use the L/mode button to switch the display so that the
Air Volume MIN and MAX readings can be viewed also.
5. Press and hold MAX/MIN for 2 seconds to return to the normal operation mode.
Multi‐Point Average Mode
1. From the normal operating mode press the U/mode button for 2 seconds to enter Multi‐
Point Average mode (the AVG display icon and the associated black dot • will switch ON).
2. Press the HOLD button momentarily to record one reading. The upper display digits will
show the reading's memory location number and the lower display will show the measured
value. Press the HOLD button again to take and store another reading; the memory location
number will increment by one and the current reading will be stored in this new memory
location.
3. Press U/mode momentarily to see the multi‐point mean (average) for all of the readings
recorded during the session (the '•AVG' display icon will flash during this process).
4. Press L/mode to view the average reading for the other available parameters.
5. Press U/mode momentarily to return to the normal operating mode.
. Wet Bulb and Dew Point temperatures are calculated based
2
(ppm) modes. The measured relative humidity or
2
7
Readings
2
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