Calibration of laboratory equipment:
ISO/IEC 17025 accreditation in five steps
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Calibration of laboratory equipment:
ISO/IEC 17025 accreditation in five steps
The international standard ISO/IEC 17025 demonstrates that a laboratory is technically competent to perform specific calibrations. For medical laboratories working under ISO 15189, the link is obvious: reliable, patient‑related results start with correctly calibrated equipment. Working with an ISO/IEC 17025‑accredited calibration lab safeguards accuracy, traceability and international recognition of measurement results.
Who grants accreditation in the Netherlands?
In the Netherlands, the Dutch Accreditation Council (Raad voor Accreditatie, RvA) assesses laboratories against ISO/IEC 17025 and grants accreditation per scope (specific calibration or testing activities). It is therefore not a generic certificate, but a recognition of technical competence within a clearly defined scope. Through the international ILAC network, mutual recognition is arranged, which is essential for institutions that collaborate internationally.
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Four technical requirements for calibration
Traceability of measurement results
Ensure an unbroken chain of comparisons to international standards. For example, a temperature probe can be verified against a reference thermometer that is traceable to the international temperature standard (ITS‑90) via a national metrology institute.
Management of equipment, references and environmental conditions:
Register measuring instruments and references in a CMMS (e.g. Ultimo) with unique IDs, periodic maintenance tasks and drift monitoring. Investigate possible deviations. By controlling the environmental conditions in the calibration room (temperature, relative humidity (RH)), you can keep the climate within specified limits.
Validation and verification of calibration methods:
Demonstrate that calibration methods are suitable in terms of repeatability, reproducibility and accuracy by following guidelines such as DKD‑R 5‑1 (temperature calibration) and EA‑4/02.
Determining measurement uncertainty:
Every calibration report for a medical laboratory device (e.g. a PCR instrument, ultra‑low freezers or incubators) must contain a substantiated calculation of the measurement uncertainty. An uncertainty budget identifies, quantifies and combines all sources (sensor limitations, operating conditions, drift over time) into a reliable interval.
The path to ISO/IEC 17025 accreditation
Obtaining ISO/IEC 17025 accreditation for calibration activities requires a thorough technical approach, with traceability, validation, measurement uncertainty and staff competence at its core.
Many technical services or laboratory technology departments follow a step‑by‑step approach towards ISO/IEC 17025 accreditation. With these investments, they can serve their customers faster, more effectively, and at lower cost. The steps below can be used as a general guideline:
- Step 1: Identify sources of uncertainty
Temperature calibration involves many uncertainty sources, such as the uncertainty of the reference temperature (master thermometer), resolution or reading errors, axial inhomogeneity of the dry‑block, and stability of the source due to fluctuations. Start by evaluating these sources of uncertainty. - Step 2: Quantify standard uncertainties
Determine the standard uncertainty and the probability distribution (e.g. normal, rectangular) for each component, and establish the corresponding standard deviations. - Step 3: Combine the standard uncertainty
Sum the individual standard uncertainties to obtain the combined standard uncertainty, which describes the spread of the measurement values. - Step 4: Determine the expanded measurement uncertainty
Multiply the combined standard uncertainty by a coverage factor (k = 2) to obtain the expanded measurement uncertainty. For a normal distribution, this roughly corresponds to a confidence level of 95%. This means that the true value lies with approximately 95% confidence within the calculated uncertainty interval. - Step 5: Competence and assurance of personnel
Ensure that laboratory technicians are demonstrably competent: provide training on ISO/IEC 17025 and on metrologically correct measurement, and train them on the specific calibration techniques once procedures and work instructions have been established. Use peer reviews and periodic observations to safeguard quality.
Tip: record all authorities and keep them up to date with a competence matrix / skills map.
Making calibration reports easier
Kalibratierapporten voor laboratoriumapparatuur moeten voldoen aan de eisen van ISO/IEC 17025. Gestandaardiseerde sjablonen helpen om alle verplichte elementen (zoals scope, herleidbaarheid, methodebeschrijving en meetonzekerheid) consistent en volledig vast te leggen. Daarnaast verminderen ze de administratieve belasting: rapporten worden sneller, uniformer en eenvoudiger auditeerbaar.
ISO/IEC 17025 accreditation for calibration activities therefore requires a solid technical foundation. Traceability, method validation, well‑substantiated measurement uncertainties, and demonstrable competencies are essential. The process is intensive, but it delivers reliable and internationally recognized measurement results. And that is exactly what laboratories need to ensure quality.
You can find more information about obtaining digital certificates at VSL on our website.
VSL performs calibrations and produces reference materials based on the national measurement standards it maintains. The associated certificates are internationally recognised under the CIPM Mutual Recognition Arrangement (CIPM MRA). A complete overview of all Calibration and Measurement Capabilities (CMCs) and of all VSL reference materials recognised under the MRA can be found in the BIPM Key Comparison Database.
Curious how you can make your calibration process 17025‑compliant more quickly, or do you need a second opinion on uncertainty budgets?
Get in touch for a quick scan or a practical working session with your team.