Accuracy: Is the closeness of the shown weight to the actual weight.
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 internal automatic adjustment or adjusting switch. It can be necessary when variations in temperature, a change of environmental conditions, change of location etc. Recommended as a daily check routine.
Animal weighing program: When an animal moves during the weighing process, a stable average value is obtained by using the HOLD key. This value remains "frozen" until the HOLD key is pressed again. Vibration free weighing
Application accuracy: Allowance for measuring uncertainty during practical use of a balance. Usually given in the appendix to the calibration certificate.
Balance: Is a weighing machine. The terms scale and balance are often used interchangeably. Historically a balance was a device that determined mass by balancing an unknown mass against a known mass as with a 2 pan libra balance. In modern weighing machines balances are usually of the design that uses a force restoration mechanism to create a force to balance the force due to the unknown mass.
Baud Rate: Is the speed of communication when using an RS-232 interface. The greater the number the faster the data is sent between 2 devices. Usually the options are between 300 to 9600 baud.
Calibration Certificate: Is documentation of measured characteristics of balances or test weights and of traceability to national standards or an accredited body such as UKAS (UK). Certificates are issued with the machine and are an additional cost.
Calibration of measuring equipment: Is the determination of the precision of a measure value without intervention in the measurement system. Example: to check a scale or balance you load a test weight upon it. The term "Calibrating" was formerly also used for adjusting.
Calibration or verification: Calibration can be carried out on any scale or balance which is in perfect working order. Calibrations are carried out to National Standards which are controlled by the state for ensuring high quality requirements according to DIN EN ISO 9000ff and other standards, e. g. in production and research.
Verification can only be carried out on type-approved balances which carry the Black M and other identifiers on the serial label.
Capacity: Is the maximum weight that can be placed on the scale or balance.
Capacity display: Generally a bar line showing the available weighing range of the scale or balance, usually located on the display
Certificate: Is written confirmation that a service has been provided in accordance with a defined requirement or accredited body such as UKAS.
Amongst other things, this can be a metrological statement as well as an ISO factory certificate, or any another lasting endorsement.
In the field of verification you receive a verification certificate
Certification : Confirmation of the achievement or compliance of a predetermined standard, such as a DIN standard such as DIN EN ISO 9000 ff. (Quality management) or DIN EN ISO/IEC 17025 (Accreditation), or a build-type approval for balances.
Commercial error limits: See reverification of balances and weights
Conformity declaration from the manufacturer: The manufacturer declares that the product fulfils the applicable EU directives. With electronic balances this is always in conjunction with the CE mark.
Conformity evaluation: Procedure for confirming warranted characteristics in accordance with recognised rules. For balances this relates to verification.
Control of measuring equipment in the QM system in conjunction with quality standards: An organisation certified to a quality standard such as DIN EN ISO 9000 ff. e. g. a production plant is obliged to adhere to a defined quality standard within the framework of its quality management system. To do this, it is imperative that you have measuring equipment which is working accurately.
DIN EN ISO 9001, December Edition 2008 states in section 7.6 "Guidance of monitoring and measuring equipment", that measuring equipment must be calibrated at defined intervals and before use. The measuring devices and measuring standards needed to do this must:
- be traced back to international or national standards.
- their measuring uncertainty must be known
- they must be marked with a clear identification
- the test must be documented
The calibration fulfils all these requirements.
Counting of single pieces: Determining a quantity by weighing. This is possible if the pieces to be counted are roughly the same weight. To do this, you establish a reference weight and then you can weigh the pieces to be counted. Counting balances display the weighed pieces as number of items immediately.
All counting balances can be switched from counting to weighing mode.
Counting resolution: The counting resolution is calculated in points from the ratio of the weighing range [Max] divided by the smallest part weight. It is a statement of counting accuracy.
Checkweighing: Is a function used to compare a weight against limits [user defined] to determine if the weight is within preset limits. Often displayed with coloured indicators.
Data interface: To connect the balance to a printer, PC, network or a second balance or display. The interfaces available are stated in the model description. Typical interfaces are, for example, RS-232, USB, LAN, DUAL, Digital I/O etc. The interface parameters can be set within the balance.
Density determination: One of the main areas of application for laboratory balances is determining densities, e.g. determining the specific weight of liquids and solids. To do this you will need a highly accurate precision balance and a density set.
It is particularly convenient if the balance can calculate and display the density right away. This is carried out by means of weighing when in the process of determining the density of liquids and solids according to the buoyancy method particularly accurate results can be obtained (Archimedes’ principle).
a) Density determination of liquids: By means of measuring the buoyancy with a glass plummet with known volume immersed in the liquid to be measured
b) Density determination of solid bodies: The sample is weighed once in air (A) and then in an auxiliary liquid of known density (B). The density of the solid (ρ) is calculated as follows:
ρ = A/(A-B) × ρ0
ρ = Density of sample
A = Weight of sample in air
B = Weight of sample in auxiliary liquid
ρ0 = Density of the auxiliary liquid
a) Pre-packaged goods control, whenever a product is sold according to its volume [cm3]. This volume is calculated with weight [g] : density [g/cm3].
b) Materials analysis
c) Density of porous materials
Draught shield: This is a protective device against the air movements during very accurate weighing procedures. Required for analytical and precision balances with readout d ≤ 1 mg.
Dual-range balance: The complete weighing range of a balance or scale is divided and has different resolutions. The change over between resolutions occurs automatically.
Electromagnetic compatibility (EMC): Is the Immunity to interference, e. g. of a balance or scale against errors on the display caused by electromagnetic emission in the local vicinity.
External test weight: Is for adjusting or checking the balance or scale accuracy. Also used to adjust the weighing range when required. The external test weight should be tested and calibrated to a known standard or to National Standards, we can carry out this work at any time.
Eccentric Loading: See Off Centre Loading.
Factory: The defined options / accessories can only be carried out at the factory or approved service company.
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.
Force Restoration: A method to determine an unknown mass by balancing the force due to the mass with another force created by the system using coils mounted in a magnetic field. Also called Servo motor or force motor.
GLP Good Laboratory Practice: also see ISO/GLP
Gravitational acceleration ➔ Gravitational force
Gravitational force very important influence for precise electronic balances. Due to the varying influence balances have to be adjusted to or at the location of use.
HACCP = Hazard Analysis and Critical Control Points: The HACCP concept is a preventative system, which is designed to guarantee the safety of foodstuffs EC regulation 852/2004 mandates the use of the HACCP concept for all companies which are involved with the production, processing and sales of foodstuffs.
Increment: These terms are often used interchangeably to indicate how well a scale displays the correct results. Increment is the value of the finest division of the scale. See also: Accuracy, readability, resolution.
Internal test weight: A internal mass used by a balance to adjust the unit when environmental changes occur such as temperature.
ISO 9000ff: Quality Management System in the form of a DIN Norm for quality assurance in a factory.
ISO/GLP: Quality Assurance Systems demand record keeping of weighing results and the correct adjusting of the balance or scale giving details of date, time and balance identification. The easiest way of obtaining this documentation is by means of a connected printer.
Levelling: The procedure to set the balance or scale so the weighing plate or platform is horizontal. This gives the balance a position that is repeatable so the results will be the same if the balance is moved. This is done using levelling feet often the machine will have a spirit level attached for convience.
Linearity / precision: The greatest deviation of the weight display of a balance or scale to the value of the respective test weight in terms of plus and minus over the whole weighing range.
Load Cell: See Strain gauge load cell.
Manufacturer's declaration of conformity: This documents that a product meets the EC directives. With electronic balances always in conjunction with CE mark.
Mass: Mass is a physical property of a material. The mass gives a material weight when gravity pulls the material toward earth. The units of mass are gram and kilogram. The terms mass and weight are often used interchangeably.
Memory: Balance contains memories, e.g. for item data, weighing data, tare weights etc.➔ PLU
Menu: A set of procedures that can be followed to change the characteristics of a balance. The menu is made up of a number of options, called parameters, that can be set at the factory or in some cases by the user.
Minimum load: lower limit of the verifiable weighing range. Is marked on the verification serial label. The function of the balance is also given below the minimum load.
Minimum sample weight: Indicates the smallest weight which can be determined, depending on the process accuracy required.
Net total: Total weight of all components of a mixture without the weight of the tare item.
Net-total weighing: weight of tare cup and weight of components memorized in two separate stores.
Optimisation of counting: see Optimisation of reference weight
Optimisation of reference weight when piece counting: The reference weight is generated automatically several times during the counting process. Increases the counting accuracy.
Off Center Loading: The ability to display the same value when a weight is placed anywhere on the weighing platform. Tested by weighing in the center of 4 quadrants on the platform. Also called eccentric loading or shift test.
Parameter: See Menu.
Parts Counting: Using a scale to determine the number of parts placed on the platform based upon the average piece weight. the piece weight is either entered by the user or determined by weighing a sample on the scales.
Percentage determination: Example: reference weight prior to drying: 50g = balance display 100 %. After drying 40 g = 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 verified balances this is stated on the identification label.
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.
Proof of compatibility: This documents the verification compatibility for combinations of weighing modules such as display devices, load cells and connecting elements.
Quality management ➔ Control of measuring equipment
Readability: These terms are often used interchangeably to indicate how well a scale displays the correct results. Readability is the value of the finest division of the scale. See also: accuracy, increment, resolution.
Readout: Smallest readable weight increment on a digital display
Readout [d]: Smallest readable weight increment on a digital display
Recipe level A: Separate memory for the weight of the tare container and the recipe ingredients (net total).
Recipe level B: Internal memory for complete recipes with name and target value of the recipe ingredients. User guidance through displays.
Repeatability: The ability to display the same value when a weight is placed on a scale more than one time. Often expressed as a standard deviation of 5 to 10 tests. Also called reproducibility.
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.
Resolution: These terms are often used interchangeably to indicate how well a scale displays the correct results. Resolution is the value of the finest division of the scale. See also: Accuracy, increment, readability.RS-232A method of sending data over wires. Often used to communicate between balances and printers or computers.
Scale: A weighing machine. The terms scale and balance are often used interchangeably. Historically a scale was a device that displayed weight by measuring a deflection, such as a spring scale. In modern weighing machines scales are usually using springs or strain gauge load cells. See also Balance.
SC-TECH ➔ Single cell technology
Semi-micro balance: Analytical balance with a readout d = 0,01 mg.
Single cell technology: The load cell consists of a single aluminium block, which gives a very high measuring quality.
Smallest part weight when counting: The smallest piece weight, which a balance can accept for piece counting. For the relevant model, enter "g/piece" in the product data table.
Shift Test: See Off Centre Loading.
Specific Gravity: See Density Determination.
Standard deviation = Reproducibility
the measure of conformity in repeat weighing (e. g. balances) subject to the same conditions. Mostly 1 d or less. Quality feature.
➔ Uncertainty of measurement of a balance
Stability: A scale is stable when the results do not change after a weight has been added to the platform.
Stable Indicator: A display that shows when the balance has determined the value displayed will no longer change.
Strain Gauge Load Cells: A method to determine mass using a mechanical component that is slightly bent by the addition of an unknown mass. the amount of bending is measured by special resistors mounted on the load cell.
Standby function: When not in use, these balances are partially switched off automatically, and when this happens there is no warm-up time when you switch them back on.
Tare: To set a display to show zero weight. This is used to remove the weight of any packing or containers so that only the weight of the material within the container is shown. The Tare value is deleted from the remaining weight that can be added to a scale. For example if a scale has capacity of 500g and then 200g is tared, the remaining capacity is 300g. Often Zero is used interchangeably.
Taring, automatic: when the tare pan is put in place the balance immediately displays zero. Saves time.
Taring subtractive: the available weighing range of a balance is reduced by the value of the tare load. Example: weighing range of a balance Max 6000 g, Tare (= container) 470 g, available weighing range 5530 g.
Temperature Compensation: The ability to correct any errors introduced to the weighing system due to changes in temperature. Usually this correction is done in software on precision balances and within the load cells of less accurate scales.
Test weights: classes of accuracy and their general relation to the types of balances:
E2 the most accurate test weights for high resolution analytical balances of verification class I ≥ 100.000 e
F1 Precision weights for analytical balances/ precision balances for verification class I/ II, up to 100,000 e
F2 Test weights for precision balances of verification class II, up to 30,000 e
M1 Precision weights for industrial and commercial balances of verification class III, up to 10,000 e
Tolerance checks: 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. (also see Weighing with tolerance ranges)
Totalising: various individual weighings are added automatically to aggregate, e. g. all individual weighings of a batch.
Totalising level C: Internal memory for complete recipes with name and target value of the recipe ingredients. User guidance through displays. Additional convenient functions, such as barcode and back calculation functions.
Traceability to the National Standard: A pre-requisite for every perfect measurement is the validated comprehensive proof that the measuring equipment can be traced back to the international or national standards. In UK the statutory binding standards are available from the NPL.
Uncertainty of measurement of a balance: 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
Validation: Documented proof, which provides a high degree of assurance that a process or procedure is suitable to fulfill a specific task.
Verification: According to the EU directive 2009/23/EG, balances must be verified if they are used as follows:
- in commercial trade when the price of a commodity is determined by weighing
- in the manufacture of pharmaceuticals in pharmacies and analysis in pharmaceutical and medical laboratories
- for official purposes
- in the production of prepackaging
- in medical applications
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:
- Class I – Analytical balance (precision balance)
- Class II – precision balance
- Class III – industrial scale (commercial scale)
Verification validity for balances: Generally 2 years for all verification categories, for control balances generally 1 year, after expiry the balance has to be reverified.
Verification value: measure of the verification tolerance, depending on balance, mostly between 1 d and 10 d
Verification value [e]: measure of the verification tolerance, depending on balance, mostly between 1 d and 10 d ➔ Readout
Weighing range [Max]: is the working range of the balance. The balance can be loaded up to the specified upper limit.
Weighing with tolerance range = Checkweighing
The lower and upper limiting values are programmed individually. Input is possible in gram, pieces or %. With tolerance checks such as dosing, portioning, sorting, Fill-to-target, classification the balance displays the value over or under the limits.
Weighing: To find the weight (mass) of an unknown against a standard known mass.
Weight: The weight of a object is the result of gravity pulling a mass toward earth. When a balance has been calibrated using a known mass then any unknown mass placed upon the scale will have a weight proportional to the known mass. The units gram and kilogram are often used to describe the weight of on object. It is common for mass and weight to be used interchangeably. A weight can also be any mass that is used, for example to put a weight on the scale.
Zero: To set the display to show zero weight. Used to reset the zero condition of a scale when small amounts of material are on the platform. Zero does not take away from the capacity of a scale. However it will only work in a very small range around the original zero condition for the scale. Zero and Tare are often combined on one key, the terms are often used interchangeably.