ThermoWorks 7000, 7250 Operating Instructions Manual

INSTRUMENT OPERATION
7000 Moisture Meter - Connect a probe

via the BNC socket located at the top of the
instrument and switch the instrument on.

7250 Moisture Meter - Remove the black
protective cap on the top of the instrument,
taking care of the moisture meter pins.

Press the pins on the moisture meter or
probe firmly to the surface to be measured.
A moisture reading will then be displayed
on the screen and the LED’s within the
keypad will illuminate to indicate the moisture
measurement. The LED displays three colors
green - OK, amber - WARNING and red ­DAMP.

MODE - The instrument incorporates five
different measurement scales. Press the MODE
button to cycle through the different scales
of measurement which are listed in the table
below.

Linear/Reference is a general scale of moisture
measurement used for all materials and is listed
to cover materials which are not covered by
the scales 1 - 4. This scale can also be used to
compare the material under test to a known dry
sample.

Readings above the fibre saturation point of the
material are only approximations. The saturation
point for different species of wood is typically in
the range of 25 to 30%.

HOLD - Press the HOLD button to freeze the
display, 'HOLD' is displayed on the screen.
Press again to continue measuring.

AUTO-OFF - The instrument will switch off
automatically after 10 minutes. To disable the
auto-off function, press and hold the HOLD
button while switching on the unit - 'auto-off
disabled' will then scroll across the screen to
confirm this.

Please note: when the unit is turned off the
auto-off function will be re-enabled.

BATTERY REPLACEMENT - Replace the
battery when the battery icon is displayed. The
meter will continue to measure accurately, but
after further usage the meter will display 'flat
bat' and 'shutdown'.

Unscrew the screw on the back of the meter
and replace with three AAA batteries, ensuring
the polarity is correct.

1762 W. 20 S. #100, Lindon, UT 84042

Ph: 801-756-7705 Fax: [phone]

www.thermoworks.com

Ref: 547-071 / 28.4.14P-14-010-02-a

7000 / 7250

Moisture Meters

Operating Instructions

Model Order Code

7000 Moisture Meter 224-070

7250 Moisture Meter 224-075

Scale Mode

Display

Icon

Range Resolution

LED Display

GREEN AMBER RED

1 Wood 1 W1 6.0 to 40.0% 0.1 <14% 14 to 20% >20%

2 Wood 2 W2 8.0 to 40.0% 0.1 <14% 14 to 20% >20%

3 Plaster P1 0.1 to 15.0% 0.1 <1% 1 to 3% >3%

4 Concrete C1 0.5 to 12.0% 0.1 <2.5 2.5 to 4% >4%

5

Linear /

Reference

Lin 0 to 1000 1 <375 375 to 575 >575

SPECIFICATIONS

6.0 to 40.0%

8.0 to 40.0%

0.1 to 15.0%

0.5 to 12.0%
0 to 1000

0.1% or 1 (Linear Scale)
±1% moisture content
3 x 1.5 volt AAA, 350 hours
1 H x 1.5 W inches
(24 H x 38 W mm) LCD
5 H x 2.2 W x 1 D inches
(128 H x 56 W x 25 D mm)

4.6 oz. (130 g)

Range Scale 1 - Wood (W1)

Range Scale 2 - Wood (W2)

Range Scale 3 - Plaster (P1)

Range Scale 4 - Concrete (C1)

Range Scale 5 - Linear/Reference (Lin)

Resolution

Accuracy

Battery
Display

Dimensions

Weight

GUIDANCE NOTES - ThermoWorks moisture
meters measure the electrical resistance of
a material and provide an indication of the
moisture content of materials. A change
from low to high in the display and green to
red on the scale shows that further tests are
appropriate. Problems arise from the 'structure'
of the material being tested, the presence of
other conductive material that may affect the
reading and also the correct method of testing.
Factors that may affect readings include:

• Density of the material - this is important

when interpreting the moisture content
that is acceptable in a particular material.
Even the same material will be variable in
composition from one example to another.

• Ability to absorb moisture - materials will

have different capabilities to hold moisture in
a satisfactory state.

• Conductivity of substance - most materials

have an inherent conductivity even if this
may be negligible. Conductivity may be
affected by carbonaceous or ferrous material
content.

• Purity of free water - the conductivity of

water varies with its purity.

• Surface treatment - cer tain surface

treatments may be conductive. Residues
may contain carbonaceous material or have
a misleading high moisture content. Wood
treatments of a salts based liquid will also
affect conductivity.

• Temperature - the electrical resistance at

any given moisture content increases as the
temperature decreases.

• Timber grain - due to the cellular structure

of timber, readings taken in the end grain will
be less accurate.

• Timber adhesive - composite materials

such as plywood will give artificially high
readings due to adhesive content.

• Homogeneity - different densities in a

material, such as knots in wood will produce
erroneous results.

• Electrical contact - it is important to

maintain good contact between the pins and
the measured substance. Hard surfaces may
require 1.2 mm diameter holes to be drilled.

• Moisture gradient - the moisture content of

a material may vary across it's section due
to various factors.

As a general rule of good practice, results
should be obtained from different areas of the
material. If in any doubt then the (Oven Dry)
test method should be used. A linear scale is
provided for relative measurement, therefore,
facilitating the comparison of unknown moisture
measurements against known standards
obtained by the (Oven Dry) test method, i.e.:

Wet Weight - Dry Weight x 100 = MC%
Wet Weight

Testing and calibration of ThermoWorks’
moisture meters is carried out using electrical
resistance as the basis for measurement.
Standard resistance values are verified by
empirical testing in accordance with OIML R

92. moisture meters - verification methods
and equipment: general provisions, issued
by Organisation Internationale De Métrologie
Légale, - 1989.

In conclusion, it must be reiterated that
the meter reading is only a guide as to the
'dampness' of the material under test. Knowing
the actual moisture content does not indicate
whether that material is 'dry' or 'wet'.

WARNING: Please ensure that
there are no electrical cables,
water or gas pipes below the
surface of material being tested.

!