Thank you for purchasing General Tools & Instruments’
MMD5NP Pinless LCD Moisture Meter. Please read this user’s
manual carefully and thoroughly before using the meter.
The MMD5NP is a non-invasive (pinless) instrument that can
detect moisture up to 3/4 in. (19mm) below the surface of
wood or building material (bricks, wallboard, etc.). The meter
infers the level of moisture from the material’s capacitance,
which the meter reads by measuring its effect on an electric
field it generates every time it is powered on.
The meter exploits two physical phenomena to make its
measurements:
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1. The linear relationship between a solid material’s moisture
level and its dielectric constant—and therefore its
capacitance.
2. The so-called fringe-field effect—the slight spreading of the
electric field produced by current flow between two electrodes
when both electrodes are on the same side of a material.
Behind the back cover of the MMD5NP 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 the
reading than moisture at the maximum penetration depth.
The MMD5NP has been calibrated at the factory for use with
wood and building material. Because the capacitance of
wood and the capacitance of building material are affected
differently by moisture, the meter measures their moisture
content on different scales.
A button on the front of the MMD5NP provides a convenient
way to switch between the two materials. Display icons
indicate which material is being tested, as well as whether
the current reading is considered low, medium or high for the
material. Any reading can be held by pushing another frontpanel button; this feature makes it possible to make a
measurement in a dark place and display it after bringing the
meter into a lighted area. The meter also is equipped with a
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buzzer whose tone rises with increasing wetness; this feature
makes it easy to detect areas of peak moisture.
The LCD displays measurements of wood’s or a building
material's moisture content as % 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 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.
The MMD5NP is powered by a 9V battery included in the
blister pack.
• Measurement hold function • Audible peak reading alert
• Auto-calibrating • Auto power off
• Low and very low battery warnings
WHAT’S IN THE BLISTER PACK
The MMD5NP comes in a plastic blister pack along with a 9V
battery and this user’s manual.
4
T OVERVIEW
C
PROD
U
The figure below shows all of the controls and indicators on
P, as well as the locations of the
D5N
the front of the M
M
sensing area and battery compartment on its back.
A
B
C
D
E
F
CD display
L
.
A
. Moisture
B
L
. Wood
C
. Building material
D
.
E
Dual-function button:
F.
level icons:
Medium;
ow;
Buzzer enabled icon
1. Power
2. Wood/Building material
ON/OFF
(press and hold)
(press briefly)
High
G
H
J
I
K
y charge
. Batter
G
ment ho
sure
. Mea
H
unction but
Dual-f
.
I
1. Buzzer
2. Measurement hold
J. Sensing area
. Battery compartment - 1 “9V”
K
battery
enable/
(press and hold)
(press briefly)
uge
ga
ld icon
o
t
n:
disable
5
SETUP INSTRUCTIONS
INSTALL BATTERY
To open the battery compartment, turn the meter over and lift
the tab on the bottom of the battery compartment cover.
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 thebutton and hold it for at
least three seconds. (To power off the meter, follow the same
instruction.)
To measure the moisture level of wood or building material,
first make sure that the correct icon appears on the left side
of the display. If it does not, press thebutton briefly to
toggle between wood and building material. Then scan the
material by gently pressing the square sensing area on the
upper back of the meter against it. The display will instantly
your material’s moisture content.
Each measurement is also accompanied by a display of one,
two or three droplet icons () at its left, indicating whether
the reading is low, medium or high for the material. The
moisture-level range for each category is different for wood
and building material; see the Specifications section on page
8 for the exact percentages.
6
Some measurement tips:
1. For maximum accuracy, press the sensing area against a
flat area of the material.
2. The material must be at least 3/4 in. thick; this 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.
3. 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).
4. 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.
To hold a measurement, press the button briefly. The
display will show the held value, along with a icon at
upper right.
To scan wood or building material for an area of peak
moisture, first make sure that the buzzer is enabled
(indicated by aicon at lower left). If the icon is absent,
press thebutton and hold it for at least three seconds.
Then scan the material while paying attention to the buzzer’s
tone. A rising tone indicates increasing moisture. When the
tone is highest, the meter is over the area of highest
moisture.
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SPECIFICATIONS
Measurement Range0 to 99.9% REL (relative reading)
for wood; 0 to 56.5% for building
material
Measurement Accuracy±3%
Measurement Resolution0.1%
Measurement Depth3/4 in. (19mm)
Display Type/Size99.9 count LCD with 0.4 in.
(10mm) high digits
Droplet Icon RangesLow/Medium/High moisture:
>0.1%/30%/70% for wood;
>0.1%/14%/42% for building
material
Sensing Area1.6 x 1.6 in. (40 x 40mm)
Auto Power OffAfter 3 to 4 minutes with 0%
reading
Low/Very Low Battery
Warning Levels<7.5V/<6.5V
Operating Temperature32° to 122°F (0° to 50C)
@<80%RH
Dimensions5.75 x 2.6 x 0.87 in.
(146 x 66 x 22mm)
Weight5.1 oz. (145g) with battery
Current Consumption<20mADC
Power Source9V battery (included)
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WARRANTY INFORMATION
General Tools & Instruments’ (General’s) MMD5NP Pinless
LCD Moisture Meter 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. The warranty period begins on the date of
purchase. You are encouraged to register your product online.
General will extend your warranty an additional 60 days
if you register at www.generaltools.com/ProductRegistry.
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 any damage due to failure of, or defect
in any product including, but not limited to, any claims
for loss of profits.
Register now at www.generaltools.com/ProductRegistry
to receive a 60-day extension to your warranty.
9
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.
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NOTES
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31
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com
Specifications subject to change without notice
NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.