Extech Instruments MO220 Users Manual

USER MANUAL

Moisture Meter

Model MO220

2

Introduction

Congratulations on your purchase of the Extech MO220 Moisture Meter. This instrument is a
conductivity moisture meter specifically designed for the wood industry.

The instrument has eight calibration scales, enabling the user to take accurate moisture
measurements in 170 wood species. Moisture measurements can be taken using the integral pin
electrodes, or using the heavy duty moisture probe.

When used with the temperature probe, the moisture measurements are automatically corrected
with respect to temperature. This meter is shipped fully tested and calibrated and, with proper use,
will provide years of reliable service.

Description

Meter Description

1. Measurement pins

2. Low battery icon

3. LCD measurement reading

4. Wood group designators

5. Units of measure

6. External moisture sensor input

7. Remote temperature probe jack

8. Temperature units button

9. Wood group letter selector button

10. Power ON-OFF button

Note that the battery compartment is located on the

rear of the instrument.

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Operation

CAUTION: The electrode measurement pins are extremely sharp. Use

when the instrument is not in use.

Basic Measurement Instructions

Manual Temperature Correction (for use without the Temperature Probe)

Automatic Temperature Correction ATC (for use with the Temperature Probe)

Auto Power OFF

care when handling this instrument. Cover the pins with the protective cap

1. Remove the cap to expose the needle electrodes OR connect the heavy duty moisture probe
socket on the right hand side of this instrument

2. Switch the meter ON by pressing the

3. Select the appropriate wood calibration scale A, B, C, E, F, G, H or J (see the Wood Calibration
Tables later in this guide) using the

4. Push the needle pins or the heavy duty moisture probe pins into the wood and observe the
reading.

5. Press and hold the power button to shut the meter off.

The instrument is calibrated for wood at 68°F (20°C). In general, wood that is warmer than 68°F
(20°C) will give higher readings and wood colder than 68°F (20°C) will give lower readings. An
approximate manual correction of 0.5% moisture content per 9°F (5°C) may be subtracted from
wood that is above 68°F (20°C). For wood that is below 68°F (20°C), a manual correction of 0.5%
moisture content per 9°F (5°C) may be added to the measured value.

1. Switch the instrument on and select the appropriate wood calibration scale as detailed earlier.

2. Using a hammer and nail of a nominal 3 mm diameter, make a hole in the wood to be tested.

3. Remove the nail and push the Temperature Probe into the hole until the tip is at the required
depth.

4. Connect the Temperature Probe into the instrument via the Temp socket.

5. Measure the wood as described earlier to obtain the automatically temperature corrected (ATC)
moisture value.

6. To read the current temperature of the wood press the T button, the LCD will display the
temperature.

7. Press the T button again to change the C/F unit of measure.

8. Press the

The meter can automatically turn itself off after several minutes. This is to conserve on battery
energy. The user can select the period of time the meter must remain idle before turning itself off
(1 through 9 minutes). The user can also elect to disable the automatic power off feature (select

00).

1. With the meter ON, simultaneously press the power and the right arrow buttons. The

2. While continuing to hold the power button, use the right arrow button to select the

3. Release both buttons when the desired value is on the LCD.

button to display moisture value again.

current time period will appear.

desired time period. Select ‘00’ to disable this feature.

button.

button.

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Manual Accuracy Check

 There are two (2) sets of calibration poles located inside the meter’s protective cover. One set is

for the 18% calibration and the other is for the 26% calibration, as marked inside the cover.

 When checking the calibration, the A scale should be selected and the temperature probe must

be disconnected.

 Touch the two measurement pins to the 18% calibration nodes and view the measurement on

the meter display. Do the same for the 26% calibration.

 When correctly calibrated, the instrument will register %H2O values in the range of 17.7 to 18.3

(18% calibration) and in the range of 25.5 to 26.5 (26% calibration).

 If the instrument reads outside the above parameters, replace the batteries. If the instrument is

still outside the parameters return for service.

Care and Maintenance

When the instrument is not in use, keep it in its pouch together with its accessories. Store the kit in a
stable, dust-free environment out of direct sunlight. Remove the batteries from the instrument if it is
to be stored for periods of more than one month, or when the low battery power symbol appears on
the display. Check the condition of accessories used with the instrument on a regular basis and
replace them if they become worn or damaged.

Battery replacement

When the low battery icon appears on the display, replace the battery as soon as practical.

1. Remove the rear battery compartment screw.

2. Remove the battery compartment door

3. Replace the two (2) ‘AAA’ 1’5V batteries

4. Replace the compartment door and secure the screw before using the meter.

5.

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 end­of-life devices to a designated collection point for the disposal of electrical and electronic
equipment.

Specifications

Display Dual measurement scale LCD with bar graph metering

Measurement principle Electrical resistance

Range Wood: 6 to 44%

Electrode length 8mm (0.3”)

Electrode pins Integrated, replaceable

Auto Power OFF After approx. 15 minutes

Power supply Two (2) ‘AAA’ 1’5V batteries

Meter housing Impact-proof plastic

Operating Temperature 0 to 40

Operating Humidity 85% Relative Humidity maximum

Dimensions 130 x 40 x 25mm (5.1 x 1.6 x 1.0”)

Weight 100g (3.5 oz)

o

C (32 to 104oF)

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