USER MANUAL
Compact Moisture Meter
Model MO50
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Introduction
Thank you for selecting the Extech MO50 Moisture Meter. The compact MO50 takes quick
Moisture level reference measurements (in percent %) on wood and building materials. The
MO50 is simple to operate and offers measurement digits, audible tones and ‘moisture drop’
icons to indicate moisture level content.
The MO50 is ideal for building restoration projects and applications where moisture detection on
floors and under carpets is critical. The MO50 is a great tool for analyzing the after-effects of
water leakage behind walls and in ceilings.
This meter is shipped fully tested and calibrated and, with proper use, will provide years of
reliable service. Please visit our website (www.extech.com) to check for the latest version of this
User Guide, Product Updates, Product Registration, and Customer Support.
Features
Displays the moisture level in wood
Displays the moisture level in building materials (wall board, sheet rock, cardboard, plaster,
concrete, and mortar)
Audible tone rate beeps faster as the moisture level increases (8 tone variations)
‘Moisture drop’ Icons display low, medium and high levels of moisture content
Easy-to-use, compact design
Display Lock freezes reading on display
Auto Power Off conserves battery power
Complete with pins (2), protective cap, and 9V battery
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Description
Meter Description
1. Measurement pins
2. LCD Display
3. Power button
4. Material Select button
5. Display Lock/Beeper button
Notes:
Battery compartment on rear of meter
Protective pin cover not shown
Display Description
1. Moisture Drop icons (1 droplet for low moisture content, 2 for medium, and 3
for high)
2. Wood mode
3. Building Material mode
4. Beeper active icon
5. Moisture reading digits
6. Percent moisture unit (relative)
7. Display Lock mode
8. Battery status icon
Fig. 1 Meter Description
Fig. 2 Display Description
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Button Description
Button
Button name
Description
Power ON-OFF
Press and hold to switch the meter ON or OFF
/
Material Select
Select Material Group (Wood, Building
Materials)
/
Display Lock / Beeper control
Short press locks reading on the display
Long press toggles the Beeper ON/OFF
Operation
Operating Steps
1. Carefully remove the protective/test cap to expose the electrode pins.
2. Switch the meter ON by pressing and holding the button. The meter emits audible tones
and the display switches on when the meter powers up. If the meter does not switch on
please check the battery in the rear compartment.
3. Momentary presses of the Material Select button toggles the Wood and Building
Material modes of operation. The displayed icons indicate the selected mode.
4. Push the electrode pins into the material under test.
5. Observe the displayed reading in percent (%), view the displayed moisture droplet icon
and listen for the audible tones.
1 moisture droplet for low readings; 2 for medium readings; 3 for high readings; refer to the
chart on the back of the meter and the reproduction in the Appendix later in this guide.
Listen, also, to the audible measurement tone (fast beeping for higher readings and slow
beeping for lower readings).There are eight (8) tone variations.
6. Press and hold the power button to switch the meter off.
Auto Power OFF (APO)
To conserve battery energy the meter automatically switches off after a three (3) minute period
of inactivity.
Display Lock
Press the Display Lock button to freeze the displayed reading. The icon is visible on the
display when Display Lock is active. Press again to return to the normal operating mode.
CAUTION: The electrode measurement pins are extremely sharp. Use care when
handling this instrument. Cover the pins with the protective cap when the instrument
is not in use.
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Beeper ON/OFF
The beeper defaults to ON. To switch the beeper OFF, press and hold the Display Lock/Audible
Beeper button . When the beeper is active the audio display icon will be visible.
Self Test cap
Turn on the MO50 meter and set the meter to Wood or Building and press the electrode pins to
the contacts on the top of the Protective/Test cap.
Expected results:
Wood: 17.0 to 19.0%
Building: 15.5 to 17.5%
If the meter reads outside of these measurements replace the batteries. If it still reads outside
of these measurements, the meter is defective and you should contact Extech.
Maintenance
Battery Replacement
When the battery status icon appears empty or flashing, replace the battery.
1. Remove the rear battery compartment cover by pushing the compartment latch.
2. Replace the 9V battery observing correct polarity.
3. Replace the compartment door securely.
4. Dispose of battery responsibly and within applicable legal regulations.
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-of-life devices to a designated collection point for the disposal of electrical and electronic
equipment.
Care and Cleaning
When the instrument is not in use please keep the protective cap in place. The electrode
pins are extremely sharp.
Store the meter in an environmentally stable, dust-free environment, out of direct
sunlight.
Remove the battery from the instrument if the meter is to be stored for long periods or if
the battery power symbol appears empty (or flashing) on the display.
To clean the meter case, wipe with a damp cloth do not use solvents or abrasives.
To clean the pins, wipe carefully with a damp cloth to remove residue; allow to dry well
before use.
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Specifications
Display LCD with multi-function indicators
Measurement type Relative Moisture Content (%)
Measurement principle Electrical resistance
Measurement indication Digital, Moisture Droplet icons (1, 2, or 3 droplets) and audible tone
with 8 levels of intensity indicating low to high moisture readings
Measurement ranges Wood
Low: 5% to 11.9%; Medium: 12% to 15.9%; High: 16 to 50%
Building Materials
Low: 1.5% to 16.9%; Medium: 17% to 19.9%; High: 20 to 33%
Resolution 0.1%
Accuracy ±3.0% for ambient conditions 22 oC to 25 oC (72 oF to 77 oF)
Electrode pin length 0.3” (8mm)
Electrode pin type Stainless steel. Integrated, replaceable
Auto Power OFF After approx. three (3) minutes
Power supply One (1) 9V Battery (rear compartment)
Consumption < 15mA
Low Battery indication When battery voltage is < 7.0VDC, approximately
Operating conditions 5~45oC (41~113oF); 80%RH max.
Storage conditions 0~50oC (32~122oF); 85%RH max.
Dimensions 170 x 65 x 30mm (6.7 x 2.6 x 1.2")
Weight 120g (4.2 oz.) without battery
Measurement Interpretation Table
WOOD (%)
BUILDING MATERIAL (%)
TOTAL RANGE >
5~50
1.5~33
LOW
5~9.9
1.5~9.9
10~11.9
10~16.9
MEDIUM
12~13.9
17~17.9
14~15.9
18~19.9
HIGH
16~19.9
20~23.9
20~29.9
24~27.9
30~39.9
28~29.9
40~50
30~33
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All rights reserved including the right of reproduction in whole or in part in any form
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