Extech Instruments RH401 User Manual
User Manual
Digital Psychrometer + IR Thermometer
Model RH401
DP
AdditionalUserManualTranslationsavailableatwww.extech.com
Wb
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Introduction
Congratulations on your purchase of the Extech RH401 Digital Psychrometer + InfraRed
Thermometer. This device measures Humidity, Air Temperature, Dew Point and Wet Bulb.
Advanced features include Infrared Non-Contact Surface Temperature Measurement, Data Hold and
programmable Auto Power Off, and an RS-232 interface for capturing readings to a PC using
optional 407752 software. The retractable probe protects the sensors when the meter is not in use.
Careful use of this meter will provide years of reliable service.
Meter Description
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13
12
11
10
15
9
14
8
7
1. Emissivity adjust indicator
2. Laser pointer on indicator
3. Low Battery indicator
4. IR Surface Temperature button
5. ON/OFF/Setup button
6. Back Light button
1
2
3
7. Laser/Down button
8. °F/°C/Up button
9. Dew Point/Wet Bulb button
4
10. % Humidity display
11. Air Temperature, Dew Point or Wet Bulb display
5
12. IR Surface Temperature display
13. Extended probe with Humidity &
6
Air Temperature Sensors
14. PC interface port
15. AC adaptor jack
Note: The battery compartment is located on the rear of the instrument
DP
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RH401-en-GB_ V1.7 1/17
Operation
Retractable Humidity and Air Temperature Sensor
Press down on the sensor, located at the top of the meter, to release it.
Humidity and air temperature will not be displayed if the sensor is not
extended.
After use, press the sensor into the stored (protected) position.
Power ON/OFF
Press the
perform a short self-test when turned on.
Press and hold the
Humidity and Air Temperature measurements
1. Hold the meter in the area to be tested.
2. Allow adequate time for readings to stabilize.
3. View the Relative Humidity measurement in the lower display.
4. View the Air (probe)Temperature measurement in the middle display
Wet Bulb and Dew Point measurements
1. To display the Dew Point measurement, momentarily press the
DP appears in the middle display.
2. Dew Point temperature is now displayed.
3. To display the Wet Bulb measurement, momentarily press the
Wb appears in the middle display .
4. Wet Bulb temperature is now displayed.
5. To display the IR surface temp – DP temp temperature press and hold the
more than 2 seconds. The
IR Temp button. The differential temperature reading can now be viewed in the top display.
6. Press and hold the
temperature.
Non-Contact InfraRed Surface Temperature measurements
1. Point the meter toward the surface to be measured.
2. Press and hold the
3. View the temperature measurement in the upper display
4. Release the
5. While holding down the
pointer on/off. The
temperature measurement is active and the laser pointer is on.
(or the button) to turn power on. The meter will
button for three seconds to turn power off.
icon will appear in the top left corner of the display, then press the
button for more than 2 seconds to toggle the display back to IR
button.
nd the reading will be held on the display until a new reading is taken.
button, press the button to toggle the laser targeting
symbol will appear in the middle left of the display indicating that surface
Press Here
button until the symbol
button until the symbol
Sensor
Extended
Sensor
Stored
button for
WARNING! The Laser button
press of the
Laser or pointing the Laser toward anyone’s eyes. Mirrored surfaces near a measurement object
can redirect the Laser, use extreme caution. Do not allow the Laser beam to be directed toward
explosive gases.
button turns on the Laser beam. Avoid looking directly into the path of the
enables/disables the Laser pointer. When enabled, each
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RH401-en-GB_ V1.7 1/17
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