Following
you find a lexicon with all explanations to the most
important terms regarding the weighing technology.
Just click on the letters of the alphabet to reach directly
the term with the respective initial letter.
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General Product Features
Power Up Test:
When the scale is turned on, all display segments will
appear for approximately 3 seconds before resetting to zero.
Stable Reading Indication:
During weighing, a segment of the display activated once a
stable reading has been reached.
Overload: If the applied
load exceeds the capacity of the scale, an "E"' will appear
on the display and the load should be removed immediately.
The scale will return to normal operation. Excessive
overloading the scale can
destroy the load cell and this is not covered under warranty.
Negative Value: When a load
is removed from the scale, any tared value will be displayed
as a negative number. To return to normal operation, the
tared value can be canceled by pressing the tare button.
Zero Function: Values can
progressively be added to a sample. By pressing the tare
key, the scale display returns to zero and an indication
appears at the upper left corner of the display.
Auto Shut-Off: To extend
battery life, the scale will automatically turn off after
approximately two to five minutes (depending on scale model)
if no active weighing is occurring.
Off: Pressing this key
turns the scale off
Search
for:
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A |
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Accuracy:
The
extent to which a given measurement agrees with the standard
value for that measurement
¹ The ability of a scale to provide a result that is as
close as possible to the actual value. Example, if a
known calibration standard weight of 200.00 grams was placed
on the iBalance 201 and the display shows 200.01 grams we
could say the accuracy of the balance is 0.01 grams or 10
milligrams. Accuracy tells how close a balance gets to the
real value. The accuracy of the scale is very sensitive
to the calibration process. It is recommended to perform a
calibration at the end user facility. If calibration is
well performed, we can usually say the accuracy of the scale
should be within +/- one display resolution with most scales.
Adjusting of measuring
equipment: precise setting of a
measure value via a professional intervention
in the measurement system
Adjusting the weighing range of a
balance: Either
with the external test weight via the adjusting program
(CAL) or with the automatic internal adjusting resp.
adjusting switch. It is necessary
with variations in temperature, a change of environmental
conditions, change of location, etc. Recommended as a daily
check routine |
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C |
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Calibration
certificate DKD:
Documentation
of measured characteristics of balances or test weights and
of traceability to the national standard.
Calibration error: The difference between what a weight
of near the full capacity of the instrument reads on the
digital display and its true mass.
Calibration of measuring equipment: determination of
the precision of a measure value without intervention in the
measurement system. E.g. to check a balance you load a test
weight upon it. The term “calibrating” was formerly also
used for adjusting
Calibration or verification: DKD calibration
(=certification) is possible for every faultless balance.
DKD calibration is a private service controlled by the state
for ensuring high quality requirements according to ISO
9000ff and others, e.g. in production and research
Verifying is only possible for balances capable of being
verified marked with M Verification (s. also "Verification")
Capacity:
The
actual or potential ability to perform, yield or withstand.
¹ The largest weight the balance is capable of
weighing.
Capacitance Loadcell:The fundamental design of a
capacitance loadcell is that of the electrical capacitor.
The loadcell contains two closely spaced, parallel,
electrically-isolated metallic surface, one of which is
essentially a diaphragm capable of slight flexing when
pressure is applied. When pressure is applied to the
capacitance loadcell a minute change occurs in distance
between the plates. The varying gap between the plates
creates in effect a variable capacitor. The resulting
capacitance is detected send to a linear comparator and
amplifier which is then processed by a microprocessor and
displayed on the LCD. Many of the older technology scales
from the 1980's use a capacitance loadcell.
Capacity display: an ascending bar graph indicates the currently selected and
optionally available weighing range
Control of measuring equipment:
Required for
quality management systems according to ISO 9000ff, GLP etc.
Measuring equipment (e.g. balances) and checking equipment (e.g.
test weights) must be controlled (=calibrated) at certain
interval for their precision
Conversions
1 grain = 0.0648 grams
1 gram = 15.4324 grains
1 gram = 0.643 pennyweights
1 gram = 0.03215 troy ounces
1.55517 grams = 1 pennyweight
28.3495 grams = 1 avoirdupois ounce
31.10348 grams = 1 troy ounce
1 kilogram = 32.15076 troy ounces
1 pennyweight = 24 grains
1 pennyweight = 0.05 troy ounces
20 pennyweights = 480 grains
20 pennyweights = 1 troy ounce
14.583 troy ounces = 1 avoirdupois pound
1 troy ounce = 1.09714 avoirdupois ounce
Cornerload:Cornerload refers to the ability of an
instrument to deliver the same weight reading for a given
object anywhere on the weighing pan. (Of course, an
instrument that does not perform acceptably with regard to
drift and repeatability cannot possibly deliver acceptable
cornerload performance.) Test this characteristic using the
same test weight that was used to test repeatability.
Position the object at various locations on the weighing pan.
The reading should be the same, within a few digits, at all
positions.
Cornerload error: Refers to
variations in the displayed weight as the object being
weighed is moved to various positions on the weighing pan.
Count:
The smallest increment of weight which the digital display
resolves. Also called "division.". |
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D |
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Data
interface/parameters: primarily RS 232C,
bidirectional. For direct connection of a printer or PC to
the balance. The interface parameters can be set on the
balance keypad. Interface cable (s. accesories software)
Declaration of conformity:
It documents
that a product meets the EG directives. With electronic
balances always in conjunction with CE sign
Density determination (previously "specific
weight"):
Determination of the density
of liquids: by means of measuring the buoyancy with a glass
plummet, 10 cm3, resolution
0.0001 g/cm3.
Determination of the density of solid matter: the density is
the ratio of weight [g]: volume [cm3]. The weight is derived
by weighing the sample in air. The volume is determined from
the buoyancy [g] of a sample, which is submerged in a
liquid. The density [g/cm3] of this liquid is known
(Archimedes´ principle).
Applications:
• Materials analysis
• Cavities in solid objects
• Density of porous materials
• Pre-packaged goods check,
whenever the merchandise is
sold according to volume
[cm3].
This volume [cm3] is calculated from the weight [g]: density
[g/cm3].
Digit:
The
smallest increment of weight that the digital display
resolves.
Divisions:
The
amount of increments a scale offers. The amount of
divisions can be determined by taking the scale's capacity
divided by the scales readability (the smallest number a
scale can display. Example the i500 features 5,000
divisions. The capacity is 500 grams and the scale's
readability or another way to say it is the numbers on the
display increase in 0.1 gram intervals. Therefore 500 / 0.1
= 5,000 divisions. Another example would be the iBalance
201 features 20,000 divisions. The capacity for the i201 is
200 grams and the scale's readability is 0.01 gram.
Therefore 200 / 0.01 = 20,000 divisions. It is the
divisons which determines the cost of a scale - not the
capacity or readability, but instead the combination of both
the capacity and readability to determine the amount of
divisions. The more divisions the better the quality of the
weighing sensor and larger the A/D converter needed to
resolve the analogic output from the weigh sensor to a
binary number for the digital display.
DKD:
DKD = German Calibration Service
Draft shield: Required for balances
with readout d < 1 mg to avoid disturbing air movements
Drift:
Drift is a
progressive (continuously upward or continuously downward)
change in the number displayed on the digital readout. The
weight readings does not stabilize, or unstable readings
with no weight applied. All analytical balances show some
uncertainty. Some do so more than others.
Two
environmental factors affect the instrument’s stability
dramatically—temperature and static electricity.
Temperature control is imperative. This includes both
control of the room temperature and maintaining the internal
temperature of the instrument. For best stability, maintain
the room temperature within two degrees constantly (day and
night). Leave the instrument plugged in and turned ON.
Static discharge can also be accomplished by putting some
ionizing devices around the weighing pan.
Drift may be
related to RFI (radio frequency interference). There is not
a lot you can do is RFI other than move the balance to a
different area where the RFI is less. Leveling of the
balance can also result in drift.
Dual-range balance: The complete weighing
range of a balance is classified and starts with reading
precision d1. Beyond this fine range reading precision is d2
(mostly 2x d1). The change-over occurs automatically |
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E |
External calibration - See detailed information about
the calibration of your scale.
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F |
Filter for adaptation to the
ambient conditions: Vibrations are
compensated due to an increase of the measurement cycles
within the balance, this means an extension of the
integration time
Flexible Bearings:
Precision components in the measuring cell (force motor)
which allow the force coil to move without friction.
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G |
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GLP:
Good Laboratory Practice (s. also GLP/ISO record keeping)
Gravitational force: Very
important influence for precise electronic balances. Due to
the varying influence balances have to be adjusted at the
location of use |
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H |
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Hysteresis:
The lag in response exhibited by a body in reacting to
changes in forces, esp. magnetic forces, affecting it.
¹
Hysteresis Error: Refers to the condition of repeatedly
weighing the same object, but obtaining different readings
on the numeric readout.
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I |
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IP protection class: the higher the
number, the less dirt and dampness intrudes into the
balance’s casing. IP 54 is dust and water resistant, IP 67
is dust and waterproof
ISO 9000ff: Quality management
system in the form of a DIN-norm for quality assurance in a
factory
ISO/GLP record keeping: Quality
Assurance Systems demand the printout of weighing results (raw
data) and the correct adjusting of the balance giving
details of date, time and balance identification. The easiest
way of obtaining this documentation
is by means of a connected printer
Instability:the tendency to behave in an
unpredictable, changeable, or erratic manner. Refers to
a displayed number which continues to vary randomly or
sporadically, rather than progressively. See
"drift."
Installation:Learn
about selecting the best location of your balance for
optimal performance.
Internal resolution:the
smallest increment of the A/D converter. It is used by the
hardware and software designers. For a scale using a
strain gauge design, the ratio
between internal and display resolution is about 4:1. It is
possible to use 1:1 ratio (Many of the cheap-junk no name
scales do this), but you will see a lot of unstable readings
by changing of 1 increment. Having stable display is the
main reason of the ratio. There are other concerns, such as
measurement speed and temperature compensations. |
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L |
Linearity/precision: Greatest
deviation of the weight display of a balance to the value of
the respective test weight in terms of plus and minus over
the whole weighing range
Linearity:
Linearity refers to the quality of delivering identical
sensitivity throughout the weighing capacity of a balance or
scale. Test this characteristic by weighing two stable
objects separately, each of approximately one half the
weighing capacity. The sum of the two readings should equal
the reading obtained when both objects are weighed together.
Linearity Calibration:
Linearity calibration utilizes three calibration points, one
at zero, center span and full span. This method minimizes
deviation between actual and displayed weights within the
balance's weighing range.
Linearity Test:
Perhaps the most obvious test of a high precision scale
would be to place a weight of accurately known value on the
weighing pan, and observe the numerical result. But there
is a better test, nearly as simple, that better reflects the
measurement accuracy. This is called the linearity test.
The linearity
test measures the ability of an instrument to have
consistent sensitivity throughout the weighing range. The
test requires several nominally equal weights, each a
fraction of the weighing capacity. The group together
should approximate the weighing range of the instrument.
For example, a 150 gram capacity scale might be tested with
three 50 gram weights.
Static electricity will cause
erratic readings. Instruments should be operated on a
static dissipating surface (antistatic mat). Operators
should stand on antistatic floor covering. Avoid the use of
plastic containers for items being weighed. Never replace
broken glass doors on instruments with plastic ones.
Maintain humidity at 65% or more. Eliminate sources of
floor vibration and air currents. On analytical balances
with glass doors, be sure the doors close fully.
Liquid Crystal Display (LCD): A numeric readout device,
often characterized by black numerals on a silver
background. |
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M |
Minimum load Min:
Lower limit of
the verifiable weighing range. Is marked on the verification
plate. The function of the balance is also given below the
minimum load
Mass tolerances - weight classifications & applications:
ANSI/ASTM
Class 1. Provides the greatest precision. Can be used as
reference standard in calibrating other weights and
appropriate for calibrating high-precision analytical
balances (from 0.01mg to 0.1mg).
ANSI/ASTM Class 2. Appropriate for calibrating
high-precision toploading balances with readabilities
ranging from 0.001g to 0.01g.
ANSI/ASTM Class 3. Appropriate for calibrating balances with
moderate precision, ranging from 0.01g to 0.1g.
ANSI/ASTM Class 4. Appropriate for student use and
semi-analytical weighing.
Min
Weight:typically used in the specifications of
counting scales(i5000,
Proscales, iBalance) The small piece weight required in a
counting mode. At the beginning of any counting process,
the scale's software needs to teach the scale what is the
unit piece weight. The scale uses the information to count
the unknown weight. |
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Net total:
Total weight of all components of a mixture without the
weight of the tare cup |
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P |
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Percentage
determination (example): Reference
weight prior to drying: 50g = balance display 100%. After
drying: 40g = balance display 80% absolute (dry mass) or 20%
relative (humidity)
Permissible ambient temperature: Measuring errors
are possible with readings either side of the limits. With
verifiable balances this is stated on the identification sign
Piece counting of single pieces
: when weighing
e.g. 10 identical pieces, the Reference quantity is 10. The
balance automatically indicates the average weight per piece.
As from now each loading of identical pieces to be counted
will be directly indicated as the quantity of pieces.
The following applies: the higher the reference quantity,
the higher the counting accuracy
Precision: The extent to which a given set of
measurements of the same sample agree with their mean.
¹ Amount of agreement between repeated
measurements of the same quantity. Also know as
repeatability. A scale can be extremely precise, but not
necessarily be accurate. Example, two balances were
evaluated for precision. Both balances: Balance "A" and
Balance "B" offers 200g x 0.001g. A 100.000 gram ASTM Class
1 test mass was place on each balance 70 times.
Balance "A"
displayed 103.005 grams 68 times and 103.004 grams 2 times.
Balance "B"
displayed 100.000 grams 10 times, 100.001 grams 11 times,
100.002 grams 9 times, 100.003 grams 17 times, 100.004 grams
17 times, 99.999 grams 4 times, 99.998 grams 10 times and
99.996 grams 2 times.
Conclusion:
Balance "A" is more precise even though the
balance measured a 100.000 test mass as 103.005. While
Balance "A" is more precise Balance "B" is more accurate
since it measured the 100.000 test mass more to the actual
mass value. |
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R |
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Readout
d: Smallest readable weight
increment on a digital display
Rear illuminated display: very contrasting
display which can also be read in the dark
Recalibration:
periodic checking of
the precision of measurement equipment / checking equipment
(e.g. balances/weights) to keep control over accuracy
Reference weight: Representative piece
weight with piece counting of same pieces. Ascertained by
taking the average of several pieces. The reference quantity
of pieces is the number of pieces selected to determine the
reference weight. Mostly between 10 and 50 pieces
Reproducibility (standard deviation):
The measure of
conformity in repeat weighing (e.g. balances)
subject to the same conditions. Mostly 1 d or less. Quality
feature
Readability: Smallest division at which the balance’s
LCD increments.
Examples:The
3001 features a 3000 gram weighing capacity and
increment in 1 gram increments (3000g x 1g.) Therefore,
the readability is 1 gram. The LCD will increment 1 g,
2 g, 3 g, 4 g, .... 1999 g, 2000 g. You will never
see 0.1 g or 0.5 g with the CS2000. The scale
manufacturer also defines the 3001 scale with an
accuracy of +/- 2 grams, but a readability of 1 gram.
Therefore the scale increments in 1 gram intervals but
it is on accurate to +/- 2 grams.
Schumann Palmscale
increments in 0.1 gram intervals. This means when
weighing item(s) on the weighing platform from 0 to 200
grams the LCD will increment from 0.0 to 0.1 g, 0.2 g,
0.3 g, ... 99.9 g, 200 g. Again you will never see
the LCD show 0.01g or 0.05 grams. The display will
ALWAYS BE IN TENTH GRAM increments. Therefore, if you
need 0.01 accuracy you need to look at
iBal 201 (200g x 0.01g)
since they don't make a scale that is 1000g x 0.1g..
The Ultraship is a dual
range scale. This means when weighing item(s) on the
weighing platform from 0 to 1000 grams the LCD will
increment from 0 to 2 g, 4 g, 6 g, ... 498 g, 500 g.
Again you will never see the LCD show 0.1g or 0.5 grams.
The display will ALWAYS BE IN TWO GRAM increments. When
the weight on the platform exceed 1000 grams
(1000g-14000G) the LCD will increment in 5 gram
intervals automatically. You have no control of this
since our factory has programmed the scale to operate in
5 gram intervals when anything is placed on the platform
over 1000 grams. Therefore, the display will show 2005
g, 2010 g, 2015, up to 14000 grams.
Reproducible: Refers to the ability of an instrument to
return the same numeric result with repeated application of
the same weight. See " hysteresis."
Resolution: The smallest increment of weight which the
numeric display can indicate. Also referred to as 'display
resolution".
Repeatability:
Repeatability refers to an instrument’s ability to
consistently deliver the same weight reading for a given
object, and to return to a zero reading after each weighing
cycle. Test this by repeatedly weighing the same object.
The best test object is a weight intended for that purpose.
It should match the weighing capacity of the instrument.
(Do not test a 200 gram capacity instrument with a test
weight less than 100 grams) When a test weight is not
available, an alternative object that is solid, non-porous,
dirt free, non-magnetic, and non-static retaining can be
used. Repeatability is sometimes referred to as "Standard
Deviation" of a set of similar weight readings.
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S |
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Semi-micro
balance: Analytical
balance with a readout d = 0.01mg
Span
Calibration:
Span calibration utilizes two calibration points, one at
zero and a choice of either half capacity or full capacity. |
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T |
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Tare:
Act of removing a known weight of an object, usually the
weighing container, to zero a scale. Taring allows you to
display the weight of the material on the scale's LCD with
the weight of the material only and not the material and
container. Most balances allow taring to 100% of the
weighing capacity.
Tare by
subtraction means that you can keep on using the tare button
providing the total mass on the platform does not exceed the
weighing capacity of the scale. Therefore, if you had the
My Weigh i5000 (5000g x 1g) and
you put a pot on the scale that weighed 1000 grams and
pressed the tare button the scale would display 0.0 and you
would now have 4000 grams weighing capacity left (5000 -
1000 = 4000 g.) Then you put 500 gram olive oil in the pot
and press the tare button the scale would display 0.0 and
you would now have 3500 grams weighing capacity left (5000 -
1000 - 500 = 3500 g.) etc, etc.
Taring,
automatic:
When the tare pan is put in place the
balance immediately displays zero. Saves time
Taring, subtractive: The disposable weighing
range of a balance is reduced by the value of the tare load.
E.g. weighing range of a balance MAX 6000 g, Tare (
container) 470 g, disposable weighing range 5530 g
Temperature Range:
Digital
scales are electronic devices. All electronic devices
contain electronic components that have temperature
coefficient. An example of this would be a resistor. If
you measure a resistor with an Ohm meter and it measures 10
ohms at 0 degrees F and you then put that resistor in an
environment chamber and bring the temperature up to 100
degrees F the resistance's value now could be 10.2 ohms.
Since the resistance value has increased this is an example
of a discrete component(a resistor) having a "positive
temperature coefficient". Well, enough with electronics
101.
How
does operating a scale above the manufacturer's operational
temperature effect you? The temperature operational range
is stated since the manufacturer has tested and confirmed
that his scale will have an accuracy (scale manufacturers'
use the word "LINEARITY") of +/- however many grams provided
you operate the scale within the stated temperature. If you
go outside of this temperature the scale may be off by a
division (in the case of the i500
<500g x 0.1g> a division is 0.1 gram so that means it
maybe off by +/-0.2 grams instead of the stated +/- 0.1
gram). Like all electronic devices it is not a good ideal
to operate them all day at excessive temperatures. Will
they operate?, Yes. Consider your computer, this also has a
temperature operating range. Can you run your computer in
an environment that is a 100 degrees?, Yes. Do you want to
do this all the time?, No because it stress the components.
Test weight external (previously
calibration weight):
Conduces to adjust or to check the
balance accuracy. The external test weight can be DKD certified
at any time, even afterwards
Test weight internal: Like test weight
external, but installed in the balance and powered by a
motor
Test weights: Classes of accuracy E,
F, M and their general relation to
the types of balances:
E2 the most accurate test weights for high resolution
analytical balances of verification category I
F1 precision weights for analytical balances
of verification category I
F2 test weights for very accurate precision
balances of verification category II
M1 precision weights for industrial and trade balances of
verification category III
Totalizing:Various
individual weighing are added automatically to aggregate,
e.g. all individual weighing of a batch
Traceability to the National Standard:
ISO 9000 requires the correctness of all checking equipment
in accordance to the defined tolerance. Thereby incorrect
measurement is prevented
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U |
Uncertainty
of measurement of a balance (= standard deviation):
Determined for
each balance according to a precisely given test method and
documented in the Calibration certificate. It depends on
various factors both internal and external. With increasing
weight the uncertainty of
measurement rises
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V |
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Verifiable/
non-verifiable balances: metrological nearly
identical. For verifiable balances certain details are
regulated by law, e.g. software changes and additional
markings
Verification: According to the EU
directive 90/ 384/ EWG balances must be verified if they are
used as follows:
a) in commercial trade when the price of a commodity is
determined by weighing
b) in the manufacture of pharmaceuticals and analysis in
pharmaceutical and medical laboratories
c) for official purpose
d) in the production of prepackaging
Every balance is tested by the metrological service and
stamped with a verification mark. Its accuracy within the
framework of permissible standard tolerances is thereby confirmed.
EU verification applies to all member states of the EU
Verification categories of balances:
I = analytical balances ; II = precision balances; III =
industrial balances
Verification of a balance with
adjusting program CAL: the
adjusting program is sealed with an official mark after the
verification. Thus the verification is only valid for the
specific place of location (s. also Gravitational force)
For the preparation of verification it is therefore necessary
to advise the place of location and postcode. See individual
model details for the information as to whether verification
can be carried out in the factory or at the place of
location
Verification value e:
Measure
of the verification tolerance, depending on balance,
mostly between 1 and 10 d (s. also Readout)
Verifying: only balances capable
of being verified can be verified officially. These balances
are marked with M. Verifiability in business is specified by
the state. It serves as consumer security
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W |
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Weighing range MAX:
is the working
range of the balance. The balance can be loaded up to the
specified upper limit
Weighing with tolerance
ranges: the
lower and upper limiting values are programmed individually.
Input is possible in gram, pieces or %. With tolerance
checks such as dosing, portioning or sorting the balance
displays the value over or under the limits
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