Extech Instruments MO57 Pinless Moisture Meter User's Manual

Extech Instruments MO57 Pinless Moisture Meter User's Manual

USER MANUAL Pinless Moisture Meter Model MO57


Thank you for selecting the Extech MO57 Pinless Moisture Meter. The MO57 employs a non destructive spherical sensor that safely glides over surfaces to measure the relative moisture in wood and other building materials (wallboard, sheet rock, cardboard, plaster, concrete, and mortar) at any angle to a depth of 10.2cm (4”). To indicate moisture level the MO57 provides a digital reading, audible tones, and ‘moisture droplet’ icons. Audible tones (eight levels of intensity) and droplet icons (1, 2, or 3) increase in proportion to increased moisture. Additional features include Auto Power OFF and Display Lock (hold). 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 Guide, Product Updates, and Customer Support.

Measurement Considerations

To measure moisture, the sensor emits and senses low-power electro-magnetic signals. The displayed reading in percent is an average of the moisture content measured over the measurement surface area and the maximum depth of penetration (10.2cm [4.0”]). 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 MO57 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. When measuring, keep hand stationary on the meter while holding and moving the meter, as hand movement can affect the readings.

Meter Description






LCD Display Power button Display Lock/Beeper button Material Select button Sensor Note: Battery compartment on rear of meter 1 2

Display Description









Droplet icons (1 for low moisture, 2 for medium, and 3 for high) Wood mode Building Material mode Beeper active icon Moisture reading Percent moisture unit (relative) Display Lock mode Battery status icon 5 4 3

Button Descriptions



Button name

Power ON-OFF Material Select (wood/building materials) / Display Lock / Beeper control



Long press to switch the meter ON or OFF Short press to toggle material groups Short press locks/unlocks reading on the display Long press toggles the Beeper ON/OFF

Powering the Meter



Long press the power button to turn the meter ON/OFF. 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. 1 MO57-en-GB_V1.1 3/20


If the battery symbol appears or if the meter does not switch ON, replace the battery. 3.


Replace the battery cover securely. Dispose of battery responsibly and within applicable legal regulations.

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 the display when Display Lock is active. Press icon is visible on again to return to the normal operating mode. 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.

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


Short press the Material Select button ( ) to toggle the Wood and Building Material modes of operation. The displayed icon indicates the selected mode. 2.

To take a measurement, hold the meter and position the sensor so that it is directly touching the surface under test (at any angle). The meter can sense moisture to a depth of 10.2cm (4”). 3.

NOTE: The position of your hand can affect the reading. Do not move or reposition the hand that holds the meter while taking measurements or when powering the unit. 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 tested surface area to the maximum penetration depth. 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.


Display Sensor Type Measurement Type Non-destructive, electro-magnetic sensing Measurement Indication Digital, Moisture Droplet icons (1, 2, or 3 droplets) and audible tone with eight levels of intensity indicating low to high moisture readings Measurement Ranges: LCD with multi-function indicators Pinless spherical sensor 4.

Long press the power button to power OFF the meter.

Relative Moisture Reading Reference Table


0.1~9.9 10.0~16.9 17.0~23.9 24.0~29.9 30.0~39.9 40.0~59.9 60.0~69.9 70.0~99.9


0.1~9.9 10.0~16.9 17.0~23.9 24.0~29.9 30.0~39.9 40.0~59.9 60.0~69.9 70.0~99.9 Wood: Low: 0.1% to 16.9%; Medium: 17.0% to 39.9%; High: 40.0 to 99.9% Building Materials: Low: 0.1% to 16.9%; Medium: 17.0% to 39.9%; High: 40.0 to 99.9% Measurement depth Resolution Accuracy Auto Power OFF Power supply Low Battery indication Low Battery APO Sensor detects to a depth of 10.2cm (4”) 0.1% Relative readings only After approx. three (3) minutes with 0% display reading. One (1) 9V Battery; Consumption: < 40mA < 7.5VDC, approximately < 5.5VDC; APO will occur in 20 seconds, approximately Operating conditions 5 ~ 45 o C (41 ~ 113 o F); 80%RH max.


Storage conditions 0 ~ 50 o C (32 ~ 122 o F); 85%RH max. Dimensions 210 x 70 x 33mm (8.3 x 2.8 x 1.3")

Battery Replacement

Weight 155g (5.5 oz.) without battery When the battery status icon 1.


appears empty or flashing, replace the battery. Remove the battery cover by pushing the compartment latch (bottom, back of meter). Replace the 9V battery observing correct polarity.

Copyright © 2017-2020 FLIR Systems, Inc.

All rights reserved including the right of reproduction in whole or in part in any form


2 MO57-en-GB_V1.1 3/20

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