Operation; Sleep Mode - Extech Instruments AN340 User Manual

Operation
Power ON‐OFF
1. Switch the meter ON by pressing the power
2. Press again to switch the meter OFF.
3. If the meter does not switch ON, check that the meter has six (6) fresh AAA batteries
installed in the rear battery compartment. Refer to the battery installation section for
details.
4. The meter can also be powered using the 9V AC power adaptor. The power adaptor connects
to the top of the meter using the jack as shown in the Description section of this guide.
Sleep mode
The meter will automatically enter the sleep mode (switch off) after twenty (20) minutes of
inactivity. To disable this feature: with the meter OFF, press and hold the SET and HOLD buttons
for two (2) seconds. The LCD will display 'n' as it switches ON. Now the sleep mode is disabled
and the user must press the power button momentarily to switch the meter OFF.
Measurements
5. Connect the sensor to the jack at the top of the meter as shown in the Description section.
Then sensor and jack are keyed to ensure proper connection. The sensor diameter is 18mm
(0.7") and the telescoping wand extends 1m (39").
6. With the meter switched ON, use the MODE button to advance from one measurement type
to the next (air velocity, air flow or volume, air temperature, relative humidity, wet bulb
temperature, and dew point temperature). Note that for air volume measurements the user
must first enter the area value for the duct under test before accurate readings can be made.
Refer to the AREA section of this guide for programming details and to the Appendix for
additional information on area measurements, calculations, and unit conversions.
7. When measuring, air must enter the vane on the side of the sensor with the printed words
AIR IN. The sensor wand can be extended using its telescoping capability up to 1m (39").
8. The measurement is indicated on the upper display digits along with the currently selected
unit of measure. To change the unit of measure, refer to the SETUP mode section. The lower
display line shows the real time clock, alternating time and date information.
9. The air temperature and relative humidity sensors are located in the slotted opening on the
sensor wand below the impeller.
10. Air velocity readings are indicated in meters per second (m/s) or feet per minute (fpm).
Temperature readings (air, dew point, or wet bulb) are indicated in °C/°F. Relative Humidity
is indicated in %. Air flow (volume) is indicated in CFM (cubic feet per minute) or CMM (cubic
meters per minute).
11. To measure relative 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.
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