General Tools MMD950 User Manual

PIN/PINLESS DEEP SENSING

MOISTURE METER

WITH SPHERICAL SENSOR

AND REMOTE PROBE

USER’S MANUAL

MMD950

Please read this manual carefully and thoroughly before using this product.

TABLE OF CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 – 5

Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

What’s in the Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 –7

Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Install Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . 7 – 12

Measuring Moisture Levels . . . . . . . . . . . . . . . . . 8 –9

Advanced Setup Instructions . . . . . . . . . . . . . . . 9 – 11

Checking Calibration . . . . . . . . . . . . . . . . . . . . 11 – 12

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Maintenance Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . 14

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INTRODUCTION

Thank you for purchasing General Tools & Instruments’ MMD950 Pin/Pinless
Deep Sensing Moisture Meter with Spherical Sensor and Remote Probe. Please
read this user’s manual carefully and thoroughly before using the meter.

The MMD950 is designed for use in woodworking, water damage restoration,
building construction and home renovation. Examples include:

• Checking for moisture on or below the surface of carpets and sub­flooring

• Measuring the moisture content of wood, drywall or concrete before
painting, wallpapering, sealing or treating

• Locating water leaks above ceilings, below floors or behind walls

• Selecting dry lumber

The meter senses the moisture level of a material using either of two
techniques:

1. Inferring the material’s electrical conductivity from the current flow

induced between a pair of steel pins placed on or into the material. The
wetter a material, the higher its conductivity. The MMD950 comes with a
remote probe consisting of a pair of replaceable stainless steel test pins
at the end of a 46 in. long cable.

2. Measuring the change in the material’s capacitance produced by

the slight spreading of an electric field generated by the meter. When
the meter is powered on, the spherical sensor at its top generates a
three-dimensional electromagnetic wave at radio frequency that
extends about 4 in. (100mm) from the meter. When the spherical
sensor is placed against a wet material, the increased capacitance of
the material distorts the wave’s electric field to an extent that can be
measured. This distortion—called the fringing field effect—is
proportional to the material’s moisture level.

WHICH SENSOR SHOULD YOU USE?

It depends on the application. The spherical sensor is the only choice for
estimating the surface or internal moisture level of materials like finished wood,
paint or wallpaper that cannot be marred by pinholes. If accurate readings are
important, the remote pin-type probe is the only option because the spherical
sensor can only provide relative readings.

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The distinction between absolute and relative readings is important to
understand. The moisture level measurements made by the remote probe’s
test pins are displayed in units of %WME (Wood Moisture Equivalent)
simultaneously on a 0-99.9 count digital LCD and a 40-LED analog bar graph.
These pin measurements are accurate within 3% of the reading plus 5 digits.

By contrast, readings made by the spherical sensor are simultaneously
displayed with no units on the LCD and on a second scale (called REL) of the
bar graph. Although the readings from the spherical sensor have no accuracy
specification, they are nonetheless useful for quickly comparing the moisture
levels of materials, or the wetness of different areas of the same material. Two
possible uses for the relative readings are:

1. Determining whether two pieces of wood to be joined have roughly the

same moisture content (which means they will dry out at the same rate
without warping).

2. Locating the source of a water leak above a ceiling, by comparing the

REL readings at various points on it. If the ceiling is level, the point with
the highest REL reading is below the source of the leak.

The biggest advantage of the spherical sensor is its ability to sense moisture up
to 4 in. below or behind the surface of a material. The remote probe’s pins can
also sense moisture just below the surface of some materials. However, for
hard materials like wood or concrete, measurements made by pins mostly
represent surface moisture content because: 1) Moisture close to the surface
has a greater effect on a reading than moisture deep below it; and 2) The
10mm (0.4 in.) long pins on the remote probe are too short to be driven deep
into a hard material.

For softer materials like soil, paper or powders, the pin measurements are
more likely to reflect the average moisture level of the material between its
surface and the penetration depth of the pins (usually far less than 0.4 in.).

Other features of the MMD950 include the following:

• Any reading (%WME or REL) can be held by pushing a front-panel button.
Doing so—called locking or “freezing” the reading—makes it possible to
make a measurement in a dark place, hold it, and display it later in a
better-lighted area.

• The 40-LED analog bar graph groups LEDs of three different colors
(green, yellow and red) into low, medium and high moisture bands. Each
readout (%WME or REL) can be accompanied by a beeper that can be

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programmed to sound in different ways in response to different moisture
levels or operations. The correlations make it easy to use sight and/or
sound to pinpoint areas of peak or relative wetness. The beeper can be
disabled without affecting measurements.

• An auto power off function that can be triggered by three, five or
10 minutes of inactivity.

• The meter can be set up to check its calibration automatically each time
it is powered on. Alternatively, it can be programmed to allow you to
check its calibration manually at any time.

• A display icon indicates when the meter’s 9V battery is low on charge.

KEY FEATURES

• Two measurement modes: Pin (conductivity-based) and pinless (based
on the fringing field effect)

• Spherical sensor gauges moisture level up to 4 in. below a surface

• Conventional test pins at end of 46 in. remote cable

• Pin measurement accuracy of ±3%

• Displays %WME and relative readings simultaneously on two displays:
0 to 99.9 count jumbo LCD with 0.9 in. (23mm) digits, and 40-dot
tri-color LED bar graph

• Manual or automatic calibration checking

• Data hold (display lock or “freeze” function)

• User-programmable beeper function, backlight function and auto power
off time

• Low battery warning

• Includes two pairs of replacement test pins

• Spare pins storage compartment

WHAT’S IN THE CASE

The MMD950 comes in a custom molded plastic case along with a remote
pin-type probe and cable, a 9V battery, two pairs of replacement pins and this
user’s manual.

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