General Tools General Tools MMD7NP Manual

PINLESS LCD MOISTURE METER

WITH TRICOLOR BAR GRAPH

USER’S MANUAL

MMD7NP

99 Washington Street
Melrose, MA 02176

Phone [phone]
Toll Free 1-800-517-8431

Visit us at www.TestEquipmentDepot.com

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

TABLE OF CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 –4

Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Product Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Install Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Measurement Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 –7

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Warranty Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Return for Repair Policy. . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Manuel de l’utilisateur (en français) . . . . . . . . . . . . . 9 – 17

Manual del Usuario (en español) . . . . . . . . . . . . . . . 18 – 27

INTRODUCTION

Thank you for purchasing General Tools & Instruments’ MMD7NP Pinless LCD
Moisture Meter with Tricolor Bar Graph. Please read this user’s manual carefully
and thoroughly before using the instrument.

The MMD7NP 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 masonry before
painting, wallpapering, sealing or treating

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

• Selecting dry lumber

The meter is a non-invasive (pinless) instrument that can detect moisture up to
3/4 in. (19mm) below the surface of the following materials: wallboard,
masonry, hardwood and softwood. It infers the level of moisture from the
material’s capacitance, which the meter measures by gauging its effect on an
electric field that the meter generates each time it is powered on.

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The meter exploits two physical phenomena to make its measurements:

1. The linear relationship between a solid material’s moisture level and its

dielectric constant—and therefore its capacitance.

2. The so-called fringing-field effect—the slight spreading of the electric

field produced by current flowing between two electrodes when both
electrodes are on the same side of a material.

Behind the back cover of the MMD7NP are two metal plates. When the meter is
powered on, the plates are given small and opposite charges. The potential
difference causes current to flow, creating a three-dimensional electric field.

When the back of the meter is placed against one side of a material with
moisture on or slightly below its surface, the increased capacitance of the
material distorts the electric field to an extent that can be sensed (as a change
in flux over the sensing area) and measured. Displayed readings reflect the
average moisture level of the material between its surface and the electric
field’s maximum penetration of 3/4 in. Moisture closer to the surface has a
greater effect on readings than moisture at the maximum penetration depth.

The MMD7NP has been calibrated at the factory for use with wallboard,
masonry, hardwood and softwood. The capacitance of wood and the
capacitance of building materials are affected differently by moisture because
they have different densities. The meter compensates for density by adjusting
the gain of its internal sensing circuitry.

Two buttons on the front of the MMD7NP provide a convenient way to switch
among the four materials. The name of the material selected appears on the
LCD. Below the LCD is a bank of colored LEDs that roughly mirrors the digital
reading above it in bar graph format, with green indicating “dry”, red indicating
“wet”, and yellow indicating an intermediate moisture level. An audible out-of­range alarm (beeper) sounds whenever wood is tested and found to have a
moisture content above 17% or when drywall or masonry is found to be more
than 70% wet.

Although the LCD displays measurements of drywall and masonry moisture
content as % readings, these are actually relative readings with no accuracy
specification. Despite that shortcoming, relative readings are useful for quickly
comparing the moisture levels of materials, or the wetness of different areas of
the same material. For example, you can use the meter to locate the source of

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a water leak above a ceiling by comparing readings at various points on it. If
the ceiling is level, the point that produces the highest reading is below the
source of the leak.

Any digital reading can be held by pushing the fourth and final front panel
button—the HOLD button. This button makes it possible to make a
measurement in a dark place and display it after bringing the meter into a
lighted area.

To extend battery life, the MMD7NP automatically powers off after two minutes
of inactivity. The instrument is powered by a “9V” battery included in the blister
pack.

KEY FEATURES

• Separate settings for drywall, masonry, softwood and hardwood

• 2 in. diagonal backlit LCD + 3-color LED bar graph

• Non-invasive technology with 3/4 in. (19mm) maximum sensing depth

• ±4% accuracy on wood

• Auto calibrating

• Reading HOLD button

• 2-minute Auto Power Off trigger

• Separate out-of-range alarms for wood and building materials

• Low battery indication

• Powered by “9V” battery

TO MANUALLY CALIBRATE THE MMD7NP

1. Power the meter on and hold it in one hand with the top in the air. Make sure
your fingers are not touching or near the inductive sensing area.

2. Press and hold the HOLD button until the display reads 101. Then release
the button; this will change the reading to 102. Wait a few seconds.
When the reading changes to 000, calibration is complete.

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PRODUCT OVERVIEW

Fig. 1 shows all of the controls, indicators and physical features of the
MMD7NP. Familiarize yourself with their names, positions and functions before
moving on to the Setup Instructions.

Fig. 1. The controls, indicators and physical features of the MMD7NP

A. HARDWOOD Mode indicator
B. SOFTWOOD Mode indicator
C. MASONRY Mode indicator
D. Drywall Mode indicator (WALL)
E. (Low battery) icon
F. Moisture level reading, as a

percentage

G. Tricolor LED bar graph

H. button: Powers meter on and

off

I.  button: Press to select mode at

left of current mode
J. HOLD button
K.  button: Press to select mode at

right of current mode
L. Held reading indicator
M. Inductive sensing area
N. Battery compartment

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SETUP INSTRUCTIONS

INSTALL BATTERY

To open the battery compartment, turn the meter over and lift the tab at the top
of the battery compartment cover (Fig. 1, Callout N). Remove the cover and set
it aside. Then plug the included “9V” battery into the wired socket inside the
compartment. The terminals of the battery and the socket mate in only one
way, with the smaller male terminal plugging into the larger female terminal.
Close the battery compartment by replacing its cover and snapping it shut.

OPERATING INSTRUCTIONS

To power on the meter, press and hold the button for at least three
seconds. (To power off the meter, follow the same instruction.)

To measure the moisture level of drywall, masonry, hardwood or
softwood, press the

the LCD (WALL is short for drywall). Then scan the material by gently pressing
the inductive sensing area (Fig. 1, Callout M) on the back of the meter against
the material. The LCD will read out the material’s moisture content as a
percentage.

Simultaneously, one or more bar graph LEDs will illuminate to place the
material’s moisture level within a spectrum bounded by “dry” and “wet”. The
color of the illuminated LED furthest to the right indicates which % band
contains the material (see the Specifications section on p. 7) for the bands’
boundaries.

To hold a reading, press the HOLD button briefly. The display will show the
held value, along with a lock icon above the % sign. If the reading is above the
alarm limit for that material, pressing the HOLD button will silence the beeper.

 or  button until the name of that material appears on

MEASUREMENT TIPS

For maximum accuracy, press the sensing area against a flat area of the
material.

Ideally, the material should be at least 3/4 in. thick. That is the meter’s
maximum measurement depth and the thickness it is calibrated for. If your
sample is too thin, the meter will measure material beneath it as well and
produce an inaccurate reading. One way to compensate for thin samples is to
stack them.

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The sample’s length and width should be at least as large as the dimensions of
the sensing area: 1.6 x 1.6 in. (40 x 40mm).

Measurements of wood are skewed by two variables: ambient humidity and the
density of the wood species. The best way to compensate for the effect of
these variables is to develop your own moisture level curves, based on your
experience working with different species of wood on a day-to-day basis.

SPECIFICATIONS

Measurement Ranges 0 to 53% for softwood

0 to 35% for hardwood

Relative readings for wallboard and masonry
Measurement Accuracy ±4% for hardwood and softwood
Maximum Sensing Depth 3/4 in. (19mm)

(in wood)
Inductive Sensor Size 1.5 x 1.5 in. (38 x 38mm)
Out-of-Range Alarm Levels >17% for wood

>70% for drywall and masonry
LCD Size 2 in. (51mm) diagonal with three 0.5 in. (13mm)

high digits
Display Resolution 1%
Bar Graph Composition 3 each green, yellow and red LEDs
LED Bands For drywall and masonry: green = 0 to 30%,

yellow = 31 to 70%, red = >70%

For wood: green = 5 to 14%,

yellow = 15 to 17%, red = >17%
Auto Power Off Trigger 2 minutes of inactivity
Operating Temperature 32° to 104°F (0° to 40°C) @ 5 to 95% R.H.
Storage Temperature 14° to 122°F (-10° to 50°C)
Dimensions 6.7 x 2.9 x 1.2 in. (170 x 75 x 30mm)
Weight 5.4 oz. (152g) without battery
Power Source (1) “9V” battery

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WARRANTY INFORMATION

General Tools & Instruments’ (General’s) MMD7NP Pinless LCD Moisture Meter
with Tricolor Bar Graph is warranted to the original purchaser to be free from
defects in material and workmanship for a period of one year. Subject to certain
restrictions, General will repair or replace this instrument if, after examination,
the company determines it to be defective in material or workmanship.

This warranty does not apply to damages that General determines to be from
an attempted repair by non-authorized personnel or misuse, alterations, normal
wear and tear, or accidental damage. The defective unit must be returned to
General Tools & Instruments or to a General-authorized service center, freight
prepaid and insured.

Acceptance of the exclusive repair and replacement remedies described herein
is a condition of the contract for purchase of this product. In no event shall
General be liable for any incidental, special, consequential or punitive damages,
or for any cost, attorneys’ fees, expenses, or losses alleged to be a
consequence of damage due to failure of, or defect in any product including,
but not limited to, any claims for loss of profits.

RETURN FOR REPAIR POLICY

Every effort has been made to provide you with a reliable product of superior
quality. However, in the event your instrument requires repair, please contact
our Customer Service to obtain an RGA (Return Goods Authorization) number
before forwarding the unit via prepaid freight to the attention of our Service
Center at this address:

Remember to include a copy of your proof of purchase, your return address,
and your phone number and/or e-mail address.

NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.

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©2016 GENERAL TOOLS & INSTRUMENTS

MAN# MMD7NP 112816

99 Washington Street
Melrose, MA 02176

Phone [phone]
Toll Free 1-800-517-8431

Visit us at www.TestEquipmentDepot.com