REED LM-81HT User manual

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Model
LM-81HT
Thermo-Hygrometer
Instruction
Manual

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Table of Contents
Features......................................................................................... 2
Specications................................................................................ 3
Instrument Description .................................................................. 4
Measuring Procedures .................................................................. 4
Additional Functions...................................................................4-5
Hold Function ............................................................................. 4
Data Record Function ................................................................. 4
Auto Power Off .......................................................................... 5
Battery Replacement..................................................................... 5
Features
• Tiny bone shape with lightweight and small size case design are
suitable for handling with one hand
• Wristlet design provides extra protection to the instrument especially
for user one hand operation
• High precision thin-lm capacitance humidity sensor with fast response
to the humidity variety
• Built-in microprocessor circuit assures excellent performance and accuracy
• Concise and compact buttons arrangement, easy operation
• Memorize the maximum and minimum value with recall
• °C/°F selectable by pressing button on the front panel.
• Multi channels display for relative humidity and temperature measured
values at the same time
• Hold function to freeze the current reading value
For service on this or any other REED product or information on other
REED products, contact REED Instruments at [email protected].

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Specifications
General Specifications
Display 8 mm LCD display
Measurement Humidity and Temperature
Operating Humidity Max. 80% RH.
Operating Temperature 0 to 50°C (32 to 122°F)
Over Input Display Indication of “- - - -”
Power Supply 006P DC 9V battery (Heavy duty type)
Power Consumption Approx. DC 6.2 mA
Weight 160g (battery included)
Dimensions 156 H x 60 W x 33 D mm (6.14 x 2.36 x 1.29”)
Accessories Optional carrying case also available (Model CA-52A)
Electrical Specifications (23 ± 5°C)
Measurement Range Resolution
Humidity 10 to 95 %RH 0.1 %RH
Temperature 32 to 122°F 0.1°F
(thermister) 0 to 50°C 0.1°C
Measurement Range Accuracy
Humidity 10 to 95 %RH < 70% RH : ± 4 %RH
≥70% RH : (4 %rdg +1.2 %RH )
Temperature
(thermister)
32 to 122°F ± 2.5°F
0 to 50°C ± 1.2°C

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Instrument Description
1 - Power Button
2 - Hold Button
3 - Max./Min. Button
4 - °C/°F Button
5 - R.H./TEMP. Sensor
6 - LCD display
7 - Battery Compartment / Cover
8 - Wristlet
Measuring Procedures
1. Power on the instrument by pressing the “Power Button” (#1, above).
2. At the mean time the reading value of relative humidity and temperature
will be displayed on the LCD display. Pressing the “°C/°F Button”
(#4, above) will select the temperature reading unit to °C or °F
3. When the meter be applied in a new environment, a few minutes are
required to reach the stable situation
Additional Functions
Hold Function
Pressing the “Hold Button” (#2, above) will freeze the current value with a
“HOLD” symbol on the display. Press again to release the hold function.
Data Record Function
1. The Data Record function records & displays the maximum and
minimum reading values. Start the Data Record function by pressing
the “Max./Min. Button” (#3, above) once. There will be a “REC”
symbol on the display.
2. With the REC symbol on the display:
(a) Press the “ Max./Min. Button “ (#3, above) once and the “Max”
symbol along with the maximum value will appear on the display.
continued ...

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NOTE: If you intend to delete the maximum value, just press the
“Hold Button” (#2, page 4) for a while, and then the display
will show the “REC” symbol only & execute the memory
function continuously.
(b) Press the “Max./Min. Button” again, the “Min” symbol along with
the minimum value will appear on the display.
NOTE: If you intend to delete the maximum value, just press the
“Hold Button” (#2, page 4) for a while, and then the display
will show the “REC” symbol only & execute the memory
function continuously.
(c) To exit the memory record function, press the “Max./Min. Button”
continuously for at least 2 seconds. The display will revert to the
current reading.
Auto Power Off
In order to prolong the battery life, the instrument has “Auto Power Off”
function. The meter will switch off automatically if no buttons are pressed
for around 10 minutes.
Battery Replacement
1. When the left corner of the LCD display shows the low battery symbol
“ ”, this indicates that replacement of the battery is then needed.
However specication measurements could still be taken for another few
hours before the meter becomes inaccurate.
2. Open the Battery Cover (#7, page 4) at the back of the meter and
remove the battery.
3. Replace with a 9V battery (alkaline or heavy-duty type)
and reinstall the cover.
For service on this or any other REED product or information on other
REED products, contact REED Instruments at [email protected].

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6
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