Extech Instruments RH401 User Manual

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User Manual

Digital Psychrometer + IR Thermometer

Model RH401

AdditionalUserManualTranslationsavailableatwww.extech.com

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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

12 11

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

7. Laser/Down button

8. °F/°C/Up button

9. Dew Point/Wet Bulb button

10. % Humidity display

11. Air Temperature, Dew Point or Wet Bulb display

12. IR Surface Temperature display

13. Extended probe with Humidity &

Air Temperature Sensors

14. PC interface port

15. AC adaptor jack Note: The battery compartment is located on the rear of the instrument

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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

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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IR Emissivity Adjustment

Emissivity is adjustable from 0.3 to 0.99. The default value is 0.95 which is the typical emissivity value of many non-metallic surfaces. If the surface to be measured is highly reflective and the emissivity is not known, cover the surface with paint or tape to improve measurement accuracy. If the emissivity of the surface is known, follow this procedure to set the value.

1. With the meter on, Press the

will flash on the top left side of the display.

2. Use the

3. When the desired setting appears in the display, press normal operation.

Material under test Emissivity Material under test Emissivity

Asphalt 0.90 to 0.98 Cloth (black) 0.98 Concrete 0.94 Skin (human) 0.98 Cement 0.96 Lather 0.75 to 0.80 Sand 0.90 Charcoal (powder) 0.96 Soil 0.92 to 0.96 Lacquer 0.80 to 0.95 Water 0.92 to 0.96 Lacquer (matt) 0.97 Ice 0.96 to 0.98 Rubber (black) 0.94 Snow 0.83 Plastic 0.85 to 0.95 Glass 0.90 to 0.95 Timber 0.90 Ceramic 0.90 to 0.94 Paper 0.70 to 0.94 Marble 0.94 Chromium Oxides 0.81 Plaster 0.80 to 0.90 Copper Oxides 0.78 Mortar 0.89 to 0.91 Iron Oxides 0.78 to 0.82 Brick 0.93 to 0.96 Textiles 0.90

Spot to Distance Ratio

The 8:1 spot to distance ratio determines the size of the measured surface area with respect to the distance the meter is held away from the surface.

up key and the down key to adjust the value.

Emissivity Factors for Common Materials

key twice to enter the Emissivity setting procedure.

again to save and return back to

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Selecting temperature units of measure (C/F)

Press and hold the

oC/o

F button momentarily to toggle the temperature units.

Automatic Power OFF

The meter automatically shuts off after a programmed period of time. To disable auto power off, with the meter off, press

and . When “n” appears, release the keys and the meter is now in Non-Sleep Mode. The power off time is adjustable from 5 to 600 seconds. To change the auto power off setting, press the

the

key to enter the setting procedure. Use the up key and the

down key to set the value. When the desired power-off time appears in the display, press

key again to save the parameters.

Backlight

Press the BKLT button to turn the display backlight on. The backlight will remain on until the BKLT button is pressed again or the meter is turned off.

Error Messages

An error message will appear on the display if the meter fails an internal diagnostic test.

1. E1 (Top display): IR temperature failure. Repair/replacement is necessary.

2. E2 (Top display): IR temperature >932°F (500°C).

3. E3 (Top display): IR temperature <-40°F (-40°C).

4. E9 (Top display): Calibration error.

5. E1 (Middle display): Temperature failure. Repair/replacement is necessary.

6. E2 (Middle display): Dew Point is out of range or Repair/replacement is necessary.

7. E3 (Middle display): Air temperature is out of range or Repair/replacement is necessary.

8. E1 (Bottom display): RH circuit error. Repair/replacement is necessary.

9. E5 (Bottom display): RH circuit error. Repair/replacement is necessary.

Setup memory

The selected display, emissivity value, auto power off time, backlight status and the laser pointer status are stored in memory and will remain in memory as the user default setting until reprogrammed by the user.

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Calibration

The following verification and calibration procedures requires a humidity chamber or the 33% and 75% RH reference bottles which are supplied with the Model RH300-CAL kit.

RH Accuracy Verification

Checking the 33% or 75% RH Calibration

1. Insert meter’s sensor into the 33% or 75% salt reference

bottle. Rotating the bottle will assist in placing it over the sensor.

2. Check the reading after 10 minutes

3. Verify that the reading is within the accuracy specification.

RH Calibration (33% and 75%)

This two-point calibration takes approximately one hour to complete.

33% Calibration

1. Turn off the meter and insert the meter sensor into the 33% salt reference bottle. Rotating the bottle will assist in placing it over the sensor.

2. Hold down the

key to turn the unit on.

3. “32.8” (reading may vary depending on temperature) will flash on the display. After 30 minutes, the flashing will stop to indicate that the 33% calibration is complete.

75% Calibration

4. Insert the meter sensor into the 75% salt reference bottle. From a steady “32.8” display press the

5. “75.2” (reading may vary depending on temperature) will flash on the display. After 30 minutes, the flashing will stop to indicate that the 75% calibration is complete and the calibration data has been saved to memory.

6. The screen will return to the normal display. Calibration is now complete.

Note: If the salt at the bottom of the calibration bottles appears dry, the bottles should be

replaced.

and keys and then press the

button to enter the 75% calibration.

33% or 75%

Cal Bottle

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RS-232 PC Communications Interface

The meter is equipped with an RS-232 PC interface jack (3.5mm phono) for connection to a PC. The cable to connect the meter to the PC is included in the optional 407752 data acquisition kit. The kit includes Windows

compatible software that allows the user to store readings in a text file and display real-time measurements in a series of selectable formats. For more information or specific operating instructions, refer to the User Guide included with the 407752 kit or contact Extech Instruments.

Specifications

Function Range and Resolution Accuracy Humidity 0.0 to 100.0% RH ±3% RH (10 to 90%) Temperature (Air) -4.0 to 122.0oF (-20 to 50oC) ±1.8oF (±1oC)

±3% reading or ±3 whichever is greater

±4% reading or ±4 whichever is greater

Temperature (InfraRed)

(@25ºC ±5ºC)

-4 to 842

F (-20 to 450oC)

-40 to -4 oF, 842 to 932oF

-40 to -20

C, 450 to 500 oC

Display Triple LCD with backlight Sensor Type Humidity: Capacitance sensor; Temperature (air): Thermistor Dew Point -90.4 to 122.0

F (-68 to 50oC) (calculated from humidity and

temperature measurements)

Wet Bulb -6.9 to 122.0

F (-21.6 to 50oC) (calculated from humidity and

temperature measurements)

IR Emissivity Adjustable from 0.3 to 0.99 IR Spot/Distance Ratio 8:1 IR Response Time 0.5 seconds Operating Conditions -4 to 122 Storage Conditions -40 to 185

F (-20 to 50oC); < 99% RH non-condensing

F (-40 to 85oC); <99% RH non-condensing

Power Supply 4 x 1.5V ‘AAA’ batteries or AC adaptor Battery Life approx. 150 hours (laser inactive); 30 hours (laser active) Dimensions / Weight 6.8x2.7x1.9” (175x70x50mm); 4.9 oz. (140g)

C/6oF

C/8oF

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Maintenance

Cleaning and storage

1. The meter should be cleaned with a damp cloth and mild detergent when necessary. Do not use

solvents or abrasives.

2. Store the meter in an area with moderate temperature and humidity (refer to the operating and

storage range in the specifications chart earlier in this manual).

Battery Replacement

When the battery power falls low, the four (4) 1.5 ‘AAA’ batteries by removing the rear battery compartment cover and accessing the battery compartment. Observe polarity when placing the batteries in the compartment. Ensure that the compartment cover is securely fastened when finished.

Repair Services

Extech offers repair and calibration services for most of the products we sell. Call the Customer Service Department for information on repair services available for this product. Repair@extech.com or call 1-603-324-7800 press 4.

symbol will appear on the lower left of the LCD. Replace the

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