Scale lexicon

The Höfelmeyer scales dictionary - everything we know about scales:

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W Y X Z

A

Accreditation
Recognition of an organisation by an independent Conformity Assessment Body (KBS) as proof of specific expertise. (e.g. DAkkS)

Adjustment / balancing of measuring instruments / scales
The metrological balancing (adjustment) of a measuring instrument to its measurand. When adjusting a balance, the weight value to be displayed is specified by applying a defined mass and assigned to the resulting raw measured value. Adjustment therefore represents an intervention in the measurement parameters which should only be carried out by specialists. If interventions are carried out on measuring instruments for legal-for-trade uses, the validity of the calibration usually expires. It must be recalibrated. Scales that have an internal adjustment, on the other hand, must also be readjusted by the operator. Calibration is then not necessary for scales of accuracy classes I or II!

Animal weighing program
When weighing live animals or dynamic products (liquids), a weight value is determined by averaging several measurements, which corresponds approximately to the stability value.

B

Buoyancy of the air
Every body experiences buoyancy in an atmospheric environment. This must be taken into account for high-precision measurements / weighing.

C

Calibration, calibrate / “manufacturer’s calibration”
The testing of measuring instruments / scales used for legal-for-trade applications in Germany by the national calibration authorities. Only measuring instruments / scales that have been placed on the market by a manufacturer on the basis of relevant certificates in conformity with the standards and directive of the European Union can be calibrated. The incorrect but common term “manufacturer’ calibration” means the conformity assessment procedure carried out by the manufacturer. Calibration is a national instrument of market surveillance and is only valid in the respective EU member state.

Calibration period / calibration validity
Measuring instruments / scales that are used for legal-for-trade service are subject to a legal period of time in Germany within which formal usability exists. It should be noted that the validity of the calibration expires immediately if the measuring instrument / scale no longer meets the requirements for use. (MessEG §31) Other EU member states have deviating legal regulations.

Calibration value (e=)
Value of the unit used to grade the measuring instrument / scale for legal-for-trade use. The calibration value corresponds to the readability of a scale in its accuracy class if e=d= is valid.

Calibration / recalibration of measuring instruments / scales
During calibration of a measuring instrument, the measured value is displayed and documented by applying a reference quantity or reference measuring standard. There is no intervention in the parameterisation of the measuring instrument. For measuring instruments in legal-for-trade use, immediate verification of calibration as a result of the calibration is not required. The documented measured values are to be evaluated with regard to compliance with error limits. Recalibration refers to repeated calibration without previous adjustment and thus enables the build-up of a calibration history. If a measuring instrument is adjusted again, this calibration history is interrupted. The first calibration after adjustment therefore does not allow a reference to the calibrations before adjustment! Note: The English term “calibration” is not always used clearly, it can sometimes be used as a synonym for "adjustment".

Calibration stamp / test stamp
Calibration stamps or test stamps are used to mark on the device when the last calibration / test was carried out on measuring instruments / scales. The stamps can also contain information about the intervals or due date for repeat inspections. The stamps are not to be confused with the state calibration labels and seals, although their purpose is comparable.

Calibration service / testing service
Private service provider who carries out and documents calibrations / tests on measuring instruments / scales using defined methods. The method can be defined by the service provider independently or in coordination. A suitability assessment can be – but does not have to be – part of this service!

Calibration interval / testing interval
Measuring and testing equipment is subject to monitoring by the organisation's quality management system. The user's organisation determines the intervals for recalibration or testing or assigns them to the legal intervals (keyword: calibration period) Calibration/testing must be carried out regularly and selected in such a way that it is appropriate to the purpose of the equipment and its risk of use.

Calibration certificate / test report
Documents the results of the calibration, which enables the user of measuring instruments to evaluate the suitability and thus the usability of the measuring instrument. An evaluation of the calibration or test results can – but does not have to be – carried out by the calibration service by means of the documented results!

Calibration in accordance with DAkkS (formerly DKD)
State-regulated method, independent of the calibration service provider, for the calibration of measuring instruments / scales. The service provider must be accredited to perform such calibration.

“can be calibrated”
An incorrect but quite common description for measuring instruments / scales which, at the time of being placed on the market by the manufacturer, have not received a conformity assessment procedure for the relevant standards and directives. The intended use of the measuring instrument / scale for legal-for-trade applications at a later date may not be possible. Therefore the intended use must be clearly clarified at the time of procurement so that the measuring instrument / scale is suitable.

Catchweigher / automatic scale for individual weighing (SWE)
Automated measuring instrument which works automatically without operator / scale for individual weighing.
Also for marking prices and weights (PAW/GAW)

CE mark
Mandatory marking for products that are made available on the market in the EU by a manufacturer.

Checkweigher / automatic control scale (SKW)
Automated measuring instrument which works automatically without operator / scale for checking pre-packaged items.

Compatibility certificate / proof of compatibility of the modules
The components for measuring instruments / scales can be manufactured by different manufacturers and are formally and technically described by means of specific certificates (assessment certificates, type test certificates). By means of the components available on the market, which are also referred to as modules of a measuring instrument, the measuring instrument manufacturer can prove suitability. The proof of compatibility is one element which must be used by the manufacturer of the scale to bring it into conformity with the Weighing Instruments Directive (2014/31/EU). Note: In the past, if proof of conformity could be provided on a scale, this was also referred to as “can be calibrated”, which no longer exists in this form.

Conformity assessment procedure / EU Declaration of Conformity
A procedure to be carried out by the manufacturer for the conform placement of measuring instruments / scales on the market. The manufacturer documents the applied conformities by means of his EU Declaration of Conformity. The user / operator must ensure the suitability of the device for the intended use by checking the EU Declaration of Conformity and, if applicable, the markings affixed to the device (type and range plates, etc.).

Examples:

  • Weighing Instruments Directive 2014/32/EU and EN 45501 for usability in legal-for-trade service as a non-automatic scale.
  • ATEX product directive 2014/34/EU for usability in certain Ex zones - etc.

Correctness
Determined and evaluated deviation of the displayed and documented measured value of the measuring instrument from the value of the respective comparison standard over the entire measuring range.

Certificate / test certificate / report
Documented confirmation of a defined requirement for a service (activity) provided Example: test certificate or test report with measured values. Note: A certificate issued does not directly represent proof of suitability.

Certification
Confirmation of the achievement of or compliance with a specified standard.

D

DAkkS / DKD (organisation)
Private-sector organisation in the function of the national accreditation body of the Federal Republic of Germany. Previously DKD = Deutscher Kalibrierdienst; collaboration between several calibration laboratories Since accreditation procedures were changed in 2009, every member state only has one national body. The relevant standard is ISO 17025.

DAkkS / DKD calibration certificate
Documented test results for measuring instruments / scales which assess the suitability of the device for the purpose of application.

Date interface / interface
A technical connection to a measuring instrument / scale which is used for the transmission of values and control functions. The design of this interface as a serial or parallel connection to external devices depends on the device type and the requirements made on the application. Alongside the conventional RS232, RS422/485 interfaces, USB, LAN/WiFi, Profinet, Profibus, Bluetooth etc. are also common.

Density / mass density
Density, also termed mass density, describes the relationship between mass (m) and volume (V). The unit of density (P; Rho) is specified in grammes [g] per cubic centimetre [cm³] or kilogrammes [kg] per cubic metre [m³].

Deviation
Value of a variable determined through calibration which deviates from the setpoint.

E

EDK load cell
The electrodynamic force compensation (EDK) as an active principle in a measuring instrument / scale is faster and more precise in direct comparison to strain gauge load cells, but also considerably more cost-intensive. Therefore EDK load cells are usually installed in checkweighers (SKW) and catchweighers (SWE) or in platform scales (NSW) with high measurement requirements.

Electromagnetic compatibility (EMC)
Interference immunity of a technical device against the effects of electromagnetic fields in its vicinity, which prevents malfunction or incorrect measurements. EN 45501:2015 requires an interference immunity of >=10V/m according to the state of the art..

Error limits (FG)
Legally permissible or generally defined deviation of the display value of a measuring instrument which is accepted as correct. Each measuring instrument displays the measured value only within the specified accuracy.

G

GLP – Good Laboratory Practice
The term: "GLP" describes the formal framework for conducting statutory tests on certain substances.

If measuring instruments / scales are used to determine quantities, they must be included in laboratory practice in the sense of a quality management system.

The suitability and usability of the measuring instrument / scale must be evaluated by means of calibration.

Gravity, force of gravity / gravitation
Due to its measuring principle, the scale as a measuring instrument is dependent on the gravimetric conditions at the place of use. The explicit adjustment of the scale to the gravity at the place of use compensates for any influence on the weight value.

If the scale is moved to another place of use, it may have to be adjusted again to the new location. For scales used in legal-for-trade applications, calibration is usually also required.

H

HACCP – Hazard Analysis and Critical Points
The abbreviation HACCP describes a quality tool for hazard analysis of critical control points in the handling and production of food.
It is therefore not a direct technical requirement on measuring instruments / scales.

High-resolution scales
“High-resolution” scales are measuring instruments which make measurement possible with high readability of the measured value. (>10,000d)
The more correct term for these is precision scales, precision balance or analytical scales.

I

ISO 9000 & ISO 9001(DIN EN)
Standards concerning the basic concepts and minimum requirements for quality management systems.

L

Linearity / correctness
An ideal scale has a complete linear progression in the sense of the correctness of the applied mass to the displayed weight value.

Levelling
A scale must be set up at the place of use in such a way that it stands horizontally on the ground without tilting. For this purpose, the scale must be aligned using the adjustable load feet and a spirit level. If this is not done, the weight may not be determined sufficiently.

M

M (measuring technology)
The “M” is part of the marking of measuring instruments in legal-for-trade use. Thus the “M” can only be included on the type plate of the measuring instruments / scales if the device has successfully been subjected to a corresponding conformity assessment procedure.

Measuring accuracy
The term: measurement accuracy implies that a measurand can be measured “exactly”. However, it is only possible to measure “accurately” to a certain extent by taking into account the measurement uncertainties. Measurement accuracy is therefore in itself only a subjective term, which is always in context with the expected measurement uncertainty. The measured value is therefore approximately correct when the measurement uncertainties are taken into account.

Measurement uncertainty
The measurement uncertainty of a measuring instrument is an objective measure of its accuracy and thus a correct statement for its appropriate use. The suitability of a measuring instrument for a specific process can be determined very easily and reliably if the measurement uncertainty is known. It is determined individually for each scale according to a precisely defined test procedure and documented in the calibration certificate. It depends on various internal and external factors of the scale and the ambient conditions. The measurement uncertainty increases with increasing load on the scale

Minimum sample weight
Specifies the smallest quantity that can be weighed depending on the required process accuracy. Not to be confused with the minimum load of a scale used for a legal-for-trade use!

Minimum load (MIN:)
Smallest net quantity which may be determined using a scale in a legal-for-trade use. Not to be confused with minimum sample weight!

Maximum permissible errors in service (VFG)
The statutory error limit for scales used in legal-for-trade applications. The VFG is the twofold error value which is permissible for a calibration. The user of the measuring instrument must ensure compliance with the VFG.

N

Named Body / Conformity Assessment Body (KBS)
Neutral and independent organisation which has been accredited for the expertise to assess measuring instruments / scales or modules, for example.

  • Official bodies are nominated formally by the German state. Example PTB, NMi etc. (Self-declaration)
  • Private bodies are accredited by the state bodies

Notified Bodies (NB)
English term for German “Benannte Stelle (BS)”: these are state-designated and supervised private inspection bodies (organisations) in the EU, which carry out conformity assessments through the mandates of manufacturers.

O

OIML
"Organisation Internationale de Metrologie Legale" This organisation issues recommendations and guidelines for measuring and test equipment in legal-for-trade use. Example: OIML R76

P

PLU – Price Look Up
This refers to data storage in price calculating shop scales for basic prices of sales items.

PRE-TARE
Tare values selectable on the scale by means of preset keys or via article database.

Pre-packages / pre-packaging (FPVO, FertigPackV, FPackV)
Way of making products available defined within the EU. The pre-packages cannot be changed imperceptibly in their labelling and the quantity contained therein without effort after they have been placed on the market. Through the harmonised, national implementation of the EU member states, this form of sealed and labelled products manufactured in the absence of the recipient of the goods is regulated by law. The Pre-packaging Regulation serves to protect the consumer. It is not limited to foodstuffs; quantity limits or to certain business relationships (B2B, B2C, etc.). It is the successor to the previously applicable national minimum quantity regulation.

PTB (Physikalisch-Technische-Bundesanstalt)
The PTB is the national metrology institute of the Federal Republic of Germany and has offices in Berlin and Braunschweig.
As a public law institution, it is subordinate to the Federal Ministry for Economic Affairs and Energy (BMWi.

Permissible ambient temperature
For measuring instruments, impermissible ambient conditions / temperatures lead to measurement errors or non-functioning of the device.

For measuring instruments / scales used in legal-for-trade applications, the ambient temperatures must be within the range specified on the rating plate.

If this operating range is exceeded, the measuring instrument / scale may not be used.

Q

Quality management system
Quality management systems / quality assurance systems e.g. in accordance with DIN EN ISO 9000 ff.

R

Reference weight for piece counting
Several identical counting pieces are weighed together for an exact average weight and divided by the number of pieces (mean value). The larger the number of reference pieces, the better the counting accuracy of the unknown quantity. Usually at least 10 reference pieces, better more, are used to determine the reference weight.

Recalibration
Periodically repeated checking of measuring equipment and test equipment for their usability

Readability [d]
Smallest readable value of a measuring instrument that can be displayed.

Resolution[d]
The total number of all values that can be displayed by a measuring instrument.
It is determined by the max value (MAX) divided by the readability "d=" or by the calibration value "e=". Examples: 15,000d, 3000e etc.

S

Standby function
The device / measuring instrument is put into an energy-saving mode.

Standard deviation
The standard deviation is a measurement of the reproducibility of a measured value.

Summing up
Any number of individual measurements, e.g. weight values, are added together to form a total quantity.

Standards
A standard is a reference object / body that is used for the adjustment or calibration of measuring instruments. In general, standards are test equipment used for testing or measuring. Test weights are standards used for the adjustment or calibration of scales.

T

Tare - subtractive
The available weighing range of a scale is reduced by the tare value. Net = MAX - Tare

Tare - additive
The available weighing range of a scale is extended by the tare value. Gross = MAX + Tare

Taring - automatic
An empty container is tared automatically in order to indicate the net fill quantity.

Tolerance checks / plus-minus
Checking whether a measured value is within a defined deviation (acceptance) of a value. Partly by visual representation of exceeding (plus) or falling below (minus).

A legal tolerance is e.g. the permissible minus deviation of a pre-package.

Type test certificate / type approval
Documented result of independent technical and formal testing of measuring instruments / scales etc. by a Conformity Assessment Body (KBS). Measuring instruments used for legal-for-trade applications must have such a certificate.

Test weight
A test weight is a mass standard (weight piece) which is used to test a measuring instrument / scale. The test weight is usually placed on the weighing pan and the displayed weight value is compared with the setpoint value of the test weight. It can also be used to adjust the scale. Special measuring instruments have internal test weights which are used for adjustment or calibration.

Test weights - accuracy classes
Test weights, like measuring instruments used in legal-for-trade use, are divided into accuracy classes. The higher the resolution of the measuring instrument, the better the accuracy class and the higher the test weight must be classified. M2, M1, F1, F2, E2, E1, E0 are the accuracy classes for test weights in ascending order and quality. Example: commercial scales of accuracy class III are to be tested with test weights of accuracy class M1. (see DIN 8127)

Test equipment
Test equipment is a measuring body (standard) that enables the testing of measuring or test equipment by means of a SET-ACTUAL comparison. Examples:

  • The test standard used for testing a scale.
  • The length standard used for testing a length measuring instrument
  • etc.

Test equipment is subject to measurement and test equipment monitoring within the meaning of ISO 9000ff, GLP.

Test equipment monitoring
Required in quality management systems in accordance with ISO 9000ff, GLP etc. Measuring equipment (e.g. scales) and test equipment (e.g. test weights) must be checked for correctness (= calibrated) at defined intervals (recalibration)

Traceability
The proof that a measured value, which is determined by means of the calibration chain/history of the standards used, is considered to be correct. Both the test standards used for adjustment and calibration, e.g. weights, and the weight values of the scale in legal-for-trade use must be traceable in order to be considered correct.

U

USP minimum sample weight
The USP minimum sample weight is a measurement of the smallest permitted sample weight in accordance with USP (United States Pharmacopeia). The USP is the counterpart to the German pharmacopoeia and also contains requirements for the suitability of the scale in chapter 41.

In addition to the absolute display accuracy (e.g. at Max), a limit for the maximum relative error due to the repeatability of the scale is also specified here. With a safety factor of 2, this may not exceed 0.1 % of the sample weight. The repeatability is usually invariable over the weighing range, so the relative error increases as the sample weight decreases. This means that there is a smallest weight that can still be weighed in correctly.

Use accuracy
Allowance for the measurement uncertainty in the practical use of a scale. It is specified in the annex to the DAkkS (DKD) calibration certificate.

V

Validation
Documented proof that a process or procedure is suitable with a high degree of certainty to fulfil a specific task.

Verification
Documented proof that a specified requirement is fulfilled.

W

Weighing range – MAX load
Maximum possible upper load limit of a scale (max. load).
For commercial scales used in legal-for-trade application, the weight display is switched off at MAX + 9e.

Wind protection
Protective device (enclosure) against disturbing air movements in precision / analytical scales (d ≤ 1 mg).

Z