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Definition: The calibration of electrical measurands is the documented determination of the relationship between the readings of a measuring instrument and the quantity values realised by traceable standards (e.g. voltage, current, resistance, frequency) under specified conditions. It provides measurement deviations and measurement uncertainties as the basis for reliable measurement results. Requirements regarding competence, traceability, measurement uncertainty evaluation and documentation are specified for calibration laboratories in DIN EN ISO/IEC 17025.

Practical relevance: Calibrated measuring equipment is an essential prerequisite for reliable testing and production data. Calibration provides measurement deviations and measurement uncertainties that are used to assess the suitability of a measuring instrument for a specified tolerance. A statement of conformity is only made if it has been requested and a decision rule has been defined. Traceability to national or international standards (e.g. PTB) is essential for quality assurance, comparability and compliance in regulated industries.

Decision-making perspectives:

• Technical decision-makers: Ensuring correct process and test data.
• Purchasing/project management: Selecting competent (e.g. accredited) calibration laboratories and defining calibration intervals.
• Science: Evaluating measurement uncertainties and validating experimental results.
• Insurance/law: Demonstrating proper monitoring of measuring equipment in the event of a liability claim.

Typical testing or verification methods: Comparison calibration with reference standards, measurement uncertainty calculation, calibration certificate with proof of traceability.

FAQ:

• Why is traceability important in calibration?
• It ensures the international comparability and legal recognition of measurement results.

Definition: The calibration of mechanical measurands is the documented determination of the relationship between the readings of a measuring instrument and the quantity values realised by traceable standards (e.g. force, pressure, torque, length) under defined mechanical and environmental conditions. It provides measurement deviations and measurement uncertainties as the basis for reliable measurement results. Requirements regarding competence, traceability, measurement uncertainty evaluation and documentation are laid down in DIN EN ISO/IEC 17025 for calibration laboratories.

Practical relevance: Calibrated test equipment is an essential prerequisite for valid results in materials testing, production monitoring and quality assurance. Display deviation, repeatability and conformity with specified tolerances are assessed. Traceability is achieved via national standards, e.g. those of the PTB. Uncalibrated measuring instruments can lead to systematic misjudgements and liability risks.

Decision-making perspectives:

• Technical decision-makers: Ensuring correct test forces (e.g. in tensile or hardness testing) and process parameters.
• Purchasing/project management: Selecting accredited calibration service providers and defining risk-based intervals.
• Science: Evaluating the measurement uncertainty and reproducibility of experimental data.
• Insurance/law: Demonstrating proper monitoring of test equipment in the context of product liability.

Typical testing or verification methods: Comparison calibration with force, pressure, torque or length standards, documentation of the traceability chain to national or international standards, issuing of a calibration certificate, where applicable with a conformity statement based on a defined decision rule.

FAQ:

• Which mechanical measurands must be calibrated regularly?
• In particular force, pressure, torque and length measuring instruments in quality-relevant testing and production processes.

Definition: The calibration of thermodynamic measurands is the documented determination of the relationship between the indications of a measuring instrument and the quantity values realised by traceable standards (e.g. temperature, relative humidity, pressure or flow) under defined thermodynamic and ambient conditions. It provides measurement errors and measurement uncertainties as the basis for reliable measurement results. Requirements for competence, traceability, measurement uncertainty assessment and documentation are laid down in DIN EN ISO/IEC 17025 for calibration laboratories.

Practical relevance: Temperature, humidity and pressure measurements are safety- and quality-critical in process plants, laboratories and testing facilities.
Calibration provides measurement errors, stability information and measurement uncertainties that are used to assess the suitability of a measuring device for specified limit values. A statement of conformity is only made if it has been commissioned and is based on a defined decision rule. Traceability is achieved via recognised reference scales and standards (e.g. ITS-90 for temperature or calibrated pressure and climate standards) and is decisive for process safety, product quality and regulatory compliance.

Decision-making perspectives:

• Technical decision-makers: Ensuring correct temperature and pressure control in plants and test rigs.
• Purchasing/project management: Definition of suitable calibration intervals as well as selection of competent, preferably accredited calibration laboratories.
• Science: Assessment of thermodynamic measurement uncertainties, reference scales (e.g. ITS-90) and long-term stability to validate experimental results.
• Insurance/law: Verification of standard-compliant monitoring of measuring equipment including traceability and decision rules in damage or compliance cases.

Typical testing or verification methods: Comparison calibration in temperature baths, furnaces or climate chambers under defined stability and equilibrium conditions, humidity and pressure calibration using traceable reference sensors or standards, determination and documentation of the measurement uncertainty including thermodynamic influencing variables (e.g. gradients, drift, stability), documentation of the traceability chain to recognised reference scales and standards, issuing of a calibration certificate where applicable with a statement of conformity based on a defined decision rule

FAQ:

• Why is temperature calibration safety-relevant?
• Incorrect temperature measurements can lead to overheating, material damage or process instability.