Extech Instruments HD300 User Manual page 6

MIN-MAX-AVG Recording Modes
The HD300 has several MIN-MAX-AVG modes described separately below. MIN-MAX-AVG
functions are available for all measurements made with the vane sensor (air velocity, air flow, and
air temperature).
Continuous Moving Average
In the Continuous Moving Average mode the meter displays the continuous average of the
measured readings for up to a 10 hour period.
1. Turn the meter ON.
2. Place the sensor in the air stream.
3. Press the MAX-MIN button in the lower keypad area for air velocity / flow.
4. Press the MAX-MIN button in the upper keypad area for air temperature.
5. The meter will begin averaging readings once per second.
Single Point Min-Max-Avg
In the Single Point Average Mode the meter takes a reading once per second and stores the
highest, lowest, and average readings.
1. Turn the meter ON.
2. Place the sensor in the air stream.
3. Press the MAX-MIN button (lower keypad area for air velocity/flow; upper keypad
area for air temperature) to enter the REC mode and display only the highest reading
(display will show REC MAX).
4. Press again to view the MIN value (display will show REC MIN). Now the display will
show only the lowest reading.
5. Press again to view the AVG value (display will show REC AVG).
6. To return to normal operation mode, press and hold the MAX-MIN button until two
tones are heard.
Multi-point Average
In the Multi-Point Average Mode the meter averages up to 20 Air Velocity readings.
1. Turn the meter ON.
2. Press and hold the AVG button for 2 seconds (until two beeps are heard). A '0' will
display in the upper right hand corner of the LCD and 'AVG' will appear on the
bottom of the LCD.
3. Place the sensor in the air stream under test.
4. Press the AVG button momentarily to capture the reading (a single tone will be
heard) and the HOLD and AVG icons will appear on the bottom of the LCD. The '0'
that was displayed previously will increment to '1'. This number will increment with
each successive press of the AVG button.
5. Take more readings (up to a maximum of 20) in the same fashion as described in
step 4.
6. The LCD will display the average of all the readings taken since the multi-point mode
was accessed in step 2.
7. To return to normal operation, press and hold the AVG button for 2 seconds (until
two tones are heard).
8. To clear the stored readings after exiting the Multi-point Average mode, press the
AREA button once.
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HD300-EU-EN V2.2 07/13