Operation - Extech Instruments RH300 User Manual

Operation

Sensor Protective Cap
Turn the protective cap (top of meter), in the direction
of the OPEN arrow to allow air into the sensor cavity.
Turn the cap in the direction of the CLOSE arrow to
protect the sensors. Always open the cap to take
measurements and close when storing.
Meter Power
Press the power button for one second to switch the meter ON/OFF. The meter will
perform a short self-test when switched ON.
Air Temperature and Relative Humidity Measurements
1. Turn the protective sensor cap (top) to the OPEN
position to expose the sensors.
2. Hold meter so that the sensors are in the test area.
3. Allow adequate time for readings to stabilize.
4. The Relative Humidity measurement (%) appears on
the top display.
5. Short press
Point temperature on the lower left display area.
6. The Wet Bulb temperature calculation (Wb) appears on the lower right.
Optional External Probe (TP890) Temperature Measurements
Connect the TP890 optional temperature probe to the jack on the right side of the
meter. The TP890 is a thermistor-type temperature probe.
Short press
area: T1 temperature, T1 minus T2 temperature (ΔT), and Dew Point (DP) temperature.
Short press
temperature (TP890 optional probe), T2 minus Dew Point temperature
Bulb (Wb) temperature.
Note: If the optional temperature sensor is not connected,
not be displayed.
Selecting Temperature Measurement Units
Long press the UNITS button to toggle the temperature measurement units (
to toggle T1 temperature or Dew
to step through three options that appear on the lower left display
to step through three options that appear on the lower right: T2
4
, and Wet
( )
, , and T2 values will
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