Pinless Moisture Meter
Symbol
Name
Description
Power ON-OFF button
Long press to switch the meter ON or OFF
/
Material Select button
Short press to select wood or building materials
/
Display Lock / Beeper control
Short press locks reading on the display
Long press toggles the Beeper ON/OFF
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USER MANUAL
Meter Description
1. LCD Display
2. Power button
3. Display Lock/Beeper button
4. Material Select button
5. Sensor (back of meter, directly behind LCD)
Model MO53
Introduction
Thank you for selecting the Extech MO53 Pinless Moisture Meter. The MO53 sensor performs noninvasive, relative moisture measurements on wood and building materials such as wallboard, sheet
rock, cardboard, plaster, concrete, and mortar. The MO53 also offers auto power off (APO), display
lock (hold), and self-calibration features.
The MO53 is ideal for building restoration projects and applications where moisture detection on
floors and under carpets is critical. The MO53 is also a handy tool for analyzing the effects of water
leakage behind walls and in ceilings.
This meter ships 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
Manual, Product Updates, and Customer Support.
Measurement Considerations
To measure moisture, the MO53 sensor emits and senses low-power electro-magnetic signals. The
displayed reading in percent is an average of the moisture content measured over the entire sensor’s
surface area (40x40mm [1.6x1.6”]) and the maximum depth of penetration (20mm [0.8”]). Moisture
that is closer to the surface has a greater effect on the displayed average than the moisture nearer to
the maximum depth of penetration.
Placing the sensor on a surface whose thickness is less than the maximum depth of penetration may
result in unreliable moisture readings; in these cases, you can stack material on top of the measured
surface to increase the thickness.
The MO53 also produces audible tones and ‘moisture droplet’ display icons to indicate moisture
level. The audible tone rate and number of droplets increase as the moisture level increases.
Note: Battery compartment on rear of meter
Display Description
1. Moisture Drop icons (one for low moisture, two for medium, and three for high)
2. Wood mode
3. Building Material mode
4. Beeper active icon
5. Moisture reading
6. Digital reading in % (relative)
7. Display Lock mode
8. Battery status
Button Description
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Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176 - TestEquipmentDepot.com
MO53-en-GB_V1.0 7/17
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Operation
WOOD (%)
BUILDING MATERIAL (%)
TOTAL RANGE >
0.1 ~ 99.9
0.1 ~ 56.5
LOW
0.1 ~ 29.9
0.1 ~ 13.9
MEDIUM
30.0 ~ 69.9
14.0 ~ 41.9
HIGH
70.0 ~ 99.9
42.0 ~ 56.5
Powering the Meter and Self-Calibration
Long press the power button to switch the meter on/off. The meter beeps and displays ON as it
powers up. If the meter does not switch on, please check the battery. The meter emits audible
tones and performs a self-calibration upon start-up. Keep the measurement sensor at least 8 to 10
cm (3 to 4”) from hands and objects during calibration. The calibration reading must not exceed 0.5.
If so, re-calibrate ensuring that hands or other objects are clear of the sensor. Note: Calibrate the
meter whenever moving from one measurement area to another.
Auto Power OFF
The meter will automatically power OFF if the reading stays 0% for 3 minutes. If the meter detects
readings, other than 0%, it will not automatically power OFF.
Display Hold Lock
Short 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.
Beeper ON/OFF
The beeper defaults to ON. To switch the beeper OFF, long press the Display Lock/Audible Beeper
button . When the beeper is active, the audio display icon will be visible.
Pinless Moisture Measurements
1. Short press the Material Select button ( ) to toggle the Wood and Building Material
modes. The displayed icons indicate the selected mode.
2. Position the sensor (located on back of meter, directly behind LCD) firmly on a flat surface so
that it directly touches the measurement area. The measurement surface area should be larger
than the sensor surface area.
3. Observe the displayed relative readings, view the displayed moisture droplet icon(s) (more
drops indicate higher moisture levels), and listen for the audible beeping (faster beeping
indicates higher moisture; there are eight intensity levels). As discussed in the Measurement
Considerations section, the displayed reading is an average of the moisture measured over the
entire sensor surface area to the maximum penetration depth. The section Relative Moisture
Reading Ranges, below, provides measurement and droplet icon ranges.
Relative Moisture Reading Ranges
Maintenance
Battery Replacement
When the battery status icon appears empty or flashing, replace the battery.
1. Remove the rear battery cover by pushing the compartment latch (bottom, back of meter).
2. Replace the 9V battery observing correct polarity.
3. Replace the battery cover 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
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.
Specifications
Display LCD with multi-function indicators
Measurement Type Pinless, non-destructive
Measurement Indication Digital relative reading in %, moisture drop icons (1, 2, or 3 droplets),
audible tone (8 intensity levels) indicating low to high moisture readings
Measurement Ranges:
Wood: Low: 0.1% to 29.9%; Medium: 30.0% to 69.9%; High: 70.0 to 99.9%
Building Materials: Low: 0.1% to 13.9%; Medium: 14.0% to 41.9%; High: 42.0 to 56.5%
Measurement depth Sensor detects to a depth of 20mm (0.8”)
Resolution 0.1%
Accuracy Relative readings only
Auto Power OFF After approx. three (3) minutes with a 0% display reading
Power Supply One (1) 9V battery, battery consumption: < 40mA
Low Battery indication < 7.5VDC, approximately
Low Battery APO < 5.5VDC; APO will occur in 20 seconds, 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
MO53-en-GB_V1.0 7/17
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