English User's Manual

User's Guide
Hygro-Thermometer + InfraRed Thermometer
Model RH101
Introduction
Congratulations on your purchase of the Extech Hygro-Thermometer plus InfraRed Thermometer.
This device measures relative humidity, air temperature (with probe), and surface temperature
(with the InfraRed function). The large, easy-to-read backlit LCD includes primary and secondary
displays plus numerous status indicators. The InfraRed feature includes a laser pointer for
convenient targeting. Careful use of this meter will provide years of reliable service.
Safety
 Use extreme caution when the laser pointer beam is on
 Do not point the beam toward anyone's eye or allow the beam
to strike the eye from a reflective surface
 Do not use the laser near explosive gases or in other
potentially explosive areas
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Meter Description
1.
Humidity/Air Temperature Probe
2.
Probe input jack
3.
Laser pointer
4.
IR Sensor
5.
Rubber holster
6.
LCD Display
7.
IR thermometer measurement button
8.
IR and Relative Humidity function buttons (4)
9.
Air Temperature function buttons (3)
10. Probe holder
11. Power ON/OFF button
12. Backlight button
Note: The battery compartment, tilt stand, tripod mount, and probe holder removal screw are
located on the rear of the instrument
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Display Layout

MAX (top of LCD): Max Hold function engaged for the Air Temperature function

HOLD (top of LCD): Data Hold function engaged for the Air Temperature function

PROBE TEMP: Reminder that the top LCD digits represent Air (Probe) Temperature

: Indicates that the laser pointer is on.

IR TEMP: Indicates that the larger LCD digits represent IR temperature measurement

MAX (bottom of LCD): Max Hold for the IR Temperature and RH function

HOLD (bottom of LCD): Data Hold for the IR Temperature function and RH function

o

%RH: Relative Humidity unit of measure

Large LCD digits at center of display for Relative Humidity and IR Temperature

Smaller LCD digits at top, right of display for Probe Temperature

o
C / F: Temperature units of measure
: Low battery indicator
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Operation
Power
Press the
button to turn power on or off.
Probe Humidity and Temperature Measurements
1. Attach the probe to the meter via the jack at the top of the meter.
2. Hold the probe in the area to be tested & allow adequate time for readings to stabilize.
3. Read the Relative Humidity (center of LCD) and Probe Temperature (top of LCD).
NOTE: Do not immerse the probe in liquid; it is intended for use in air only.
InfraRed (Non-Contact) Temperature Measurements
1. The IR sensor is located at the top of the meter.
2. Point the sensor toward the surface to be measured.
3. Press and hold the large red IR button to begin measuring the surface
temperature of a desired target. IR TEMP and
will appear on the display. The
laser pointer will switch on to help aim the meter.
4. The measured IR surface temperature will appear at the center of the LCD (larger
digits). The temperature displayed is the temperature of the area within the spot.
5. When the red IR button is released, the laser pointer will switch off and the
reading will freeze (data hold) on the display for approx 10 seconds.
6. Note that the probe (Air Temperature wand) continues to monitor temperature
during IR tests and its temperature is displayed on the top of the LCD (smaller
digits).
7. After approx. 10 secs. the meter defaults to the Humidity and Air Temperature
display.
IR
Spot
Automatic Power OFF
To conserve battery life the meter automatically shuts off after 10 minutes.
o
o
F/ C buttons
The Air Temperature and the IR Temperature units can be selected by the user. For Air
o o
Temperature, press the F/ C button on the bottom left. For the IR temperature units, press the
o o
F/ C button at the center of the meter.
Data Hold Buttons
Displays can be held (frozen) at any time by pressing the HOLD button. For Air Temperature, use
the HOLD button on the bottom right. For IR Temperature and for Relative Humidity, use the HOLD
button on the right center of the meter. Press HOLD again to exit the mode. Note that in IR
temperature mode Data Hold is automatically engaged when the red IR button is released.
MAX Buttons
Press the MAX button (bottom of meter for Air Temperature; center of meter for IR temperature and
Relative Humidity) to display only the highest reading. The displayed measurement will now only
change when a higher reading is detected. Press the MAX button again to exit this mode.
Backlight
Press the backlight
button to turn the light on. Press again to turn it off.
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InfraRed Measurement Considerations

When taking IR measurements the meter automatically compensates for ambient temperature
changes. Note that it may take up to 30 minutes to adjust to extremely wide ambient changes.

Low temperature measurements quickly followed by high temperature measurements may
require several minutes to stabilize as a result of the IR sensor cooling process.

If the surface of the object under test is covered with frost, oil, grime, etc., clean before taking
measurements.

If an object's surface is highly reflective apply masking tape or flat black paint before measuring.

Steam, dust, smoke, etc. can obstruct measurements.

To find a hot spot, aim the meter outside the area of interest then scan across (in an up and
down motion) until the hot spot is located.
IR Theory
IR thermometers measure the surface temperature of an object. The meter’s optics sense emitted,
reflected, & transmitted energy that is collected and focused onto the meter’s detector. The meter’s
circuitry translates this information into an LCD reading.
IR Field of View
Ensure that the desired target is larger than the spot size as shown in the diagram below. As the
distance from an object increases, the spot size of the area measured by the meter becomes larger.
The meter’s field of view ratio is 8:1, meaning that if the meter is 8 inches from the target, the
diameter (spot) of the object under test must be at least 1 inch. Other distances are shown below in
the field of view diagram.
Distance to Object in inches
10”
8”
6”
0.75”
1”
1.25”
Diameter of Spot in inches
6
12”
1.5”
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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.
Battery Replacement
The battery symbol
appears on the lower right of the LCD when the 9V battery needs to be
replaced.
Replace the 9V battery as follows:
1. Turn the meter off and disconnect the air temperature probe.
2. Remove the large flat-head screw on the rear of the meter to remove the probe holder.
3. Remove the rubber holster that surrounds the entire meter by pulling it over the top of the meter.
4. Remove the small Phillips head screw on the rear of the meter.
5. Open the battery compartment and replace the 9V battery.
6. Re-assemble the meter before operating.
Never dispose of used batteries or rechargeable batteries in household waste.
As consumers, users are legally required to take used batteries to appropriate
collection sites, the retail store where the batteries were purchased, or wherever
batteries are sold.
Disposal: Do not dispose of this instrument in household waste. The user is obligated to take end-oflife devices to a designated collection point for the disposal of electrical and electronic equipment.
Other Battery Safety Reminders
o Never dispose of batteries in a fire. Batteries may explode or leak.
o Never mix battery types. Always install new batteries of the same type.
WARNING: To avoid electric shock, do not operate the meter until the battery cover is in place and
fastened securely.
NOTE:: If your meter does not work properly, check the fuses and batteries to make sure that they are
still good and that they are properly inserted.
Calibration
A humidity calibration adjustment is located in the battery compartment.
Cal
Adjust
1. Remove the battery door and move the battery to one side.
2. Place the humidity probe in a humidity chamber or humidity calibration bottle
and wait 20 minutes
3. Turn the meter on and turn the adjustment until the humidity reading on the
display agrees with the calibration source.
Battery
Compartment
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Specifications
Function
Range and Resolution
Accuracy
Humidity
10.0 to 95.0% RH
± 3.5% RH
Air Temperature
-20 to 60 C (-4 to 140 F)
IR Temperature
o
o
o
o
-50.0 to -20.0 C (-58.0 to -4.0 F)
o
o
o
93 C to 204 C (200 to 400 F)
o
o
o
204 C to 500 C (400 to 932 F)
Display
Sensor Type
Response Time
Accuracy note
Sampling Rate
InfraRed Emissivity
IR Field of View
Laser power
IR Spectral Response
Operating Conditions
Storage Conditions
Power Supply
Battery Life
Dimensions / Weight
Patent Notice
o
o
± 5 C (± 9 F)
o
-20.0 to 93.3 C (-4.0 to 199.9 F)
o
o
± 2.0 C (± 3.0 F)
o
o
o
± 2% of rdg or ± 2 C (± 4 F)
± 3% of rdg
Dual LCD with Backlight and status indicators
Humidity: Precision capacitance sensor
Temperature: Thermistor (probe) and InfraRed
IR Temperature: 0.5 seconds; Probe Temperature and Relative
Humidity: 3 minutes
Accuracy is specified for the following ambient temperature range: 18 to
28°C (64 to 82°F)
2.5 samples per second
0.95 (fixed)
D/S = Approx. 8:1 ratio (D = distance, S = spot)
Less than 1mW
6 to 14 m (wavelength)
o
o
0 to 50 C (32 to 122 F); < 80% RH non-condensing
o
o
-10 to 60 C (14 to 140 F); <80% RH non-condensing
9V Battery with auto power off (after 10 minutes)
Approx. 24 hours (if Backlight and Laser are used continuously the
battery life is reduced to 2 to 3 hours approx.)
150 x 72 x 35mm (5.9 x 2.8 x 1.4”); 235g (8.3 oz)
U.S. Patent 7168316
Emissivity
Most organic materials and painted or oxidized surfaces have an emissivity of 0.95 (fixed setting in
the model RH101). Inaccurate readings will result when measuring shiny or polished surfaces. To
compensate, cover the surface under test with masking tape or flat black paint. Allow time for the
tape to reach the same temperature as the material underneath then measure the temperature of
the tape or the painted surface.
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Thermal Emissivity Table for Common Materials
Material
Emissivity
Asphalt
0.90 to 0.98
Concrete
0.94
Cement
0.96
Sand
0.90
Earth
0.92 to 0.96
Water
0.67
Ice
0.96 to 0.98
Snow
0.83
Glass
0.85 to 1.00
Ceramic
0.90 to 0.94
Marble
0.94
Plaster
0.80 to 0.90
Mortar
0.89 to 0.91
Brick
0.93 to 0.96
Cloth (black)
0.98
Human skin
0.98
Lather
0.75 to 0.80
Charcoal (powder)
0.96
Lacquer
0.80 to 0.95
Lacquer (matt)
0.97
Rubber (black)
0.94
Plastic
0.85 to 0.95
Timber
0.90
Paper
0.70 to 0.94
Chromium oxides
0.81
Copper Oxides
0.78
Iron Oxides
0.78 to 0.82
Textiles
0.90
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