ISO/IEC 17025 Calibration Explained for UAE Laboratory Managers

What does "traceable" mean in a calibration context?

Traceability in metrology means that a measurement result can be related — through an unbroken chain of calibrations — to a national or international measurement standard. For mass (weighing), this chain runs: your balance → the calibration laboratory's reference weights → the national metrology authority (in the UAE, the Ministry of Industry and Advanced Technology, which absorbed ESMA in 2020) → the International Bureau of Weights and Measures (BIPM) and its realisation of the International System of Units (SI).

A calibration certificate is only truly "traceable" if it documents this chain explicitly: the certificate must state the reference standards used, their calibration source, and the measurement uncertainty contributed at each level. A&D Gulf's calibration certificates reference internationally traceable reference weights and document that chain.

What must a calibration certificate contain?

An ISO/IEC 17025-compliant calibration certificate for a weighing instrument must document: the identity of the instrument (model, serial number, manufacturer); the reference standards used and their traceability; the calibration method applied; the test points (load values at which the balance was tested); the results at each test point (reading, error, repeatability); the expanded measurement uncertainty (typically at k=2, 95% confidence level); the environmental conditions during calibration; and the date of calibration and next recommended calibration date.

Certificates that state only "pass/fail" without numerical data — a common failing of low-cost calibration services — do not meet ISO/IEC 17025 requirements and should not be accepted for GMP, ISO 9001, or laboratory accreditation audits.

Calibration, adjustment, and verification are three different things

The three terms are used loosely in industry, and the looseness causes audit findings. Calibration measures and documents how your balance actually reads against reference standards — it changes nothing on the instrument, it produces data. Adjustment changes the instrument's response to bring its readings closer to true — the thing most people picture when they say "calibrate". Verification is a conformity decision: comparing calibration results against a defined tolerance and declaring pass or fail, as in legal-for-trade verification under UAE metrology law.

A proper calibration certificate therefore records "as found" readings (how the balance read when the technician arrived) and, if adjustment was performed, "as left" readings (how it read afterwards). The as-found data is the part your quality system actually depends on — it tells you whether every weighing since the previous calibration was made on an in-tolerance instrument.

How often must balances be calibrated in the UAE?

UAE regulations do not specify a mandatory calibration interval for all industries, but sector-specific requirements apply. Note that the standards most often cited at us do not fix the number either: EU GMP Chapter 3 §3.41 — the actual source of the quoted phrase — requires measuring, weighing, recording and control equipment to be calibrated and checked "at defined intervals by appropriate methods", and ICH Q7 §5.30 requires calibration "according to written procedures and an established schedule"; GMP Annex 15 is Qualification and Validation and sets no calibration interval at all. Annually for analytical balances and semi-annually for high-use production floor balances is common practice rather than a published requirement. UAE pharmaceutical facilities are licensed by the Ministry of Health and Prevention (MOHAP), with pharmaceutical regulation now largely under the Emirates Drug Establishment (EDE) since 2023, and the interval is yours to justify on risk. ISO 9001:2015 Clause 7.1.5 requires calibration "at specified intervals or before use" against national or international measurement standards.

For ISO/IEC 17025-accredited laboratories, the laboratory's accreditation body (EIAC or ENAS) will specify calibration intervals as part of the accreditation conditions — typically annually. Weighing instruments used in trade are separately subject to legal metrology control by the Ministry of Industry and Advanced Technology; confirm the current requirement and re-verification interval for your instrument class with MOIAT, as these are set by the regulator rather than by the calibration standard. In Dubai the verification itself is carried out by Dubai Municipality's Dubai Central Laboratory under authorisation from MOIAT.

Does internal calibration replace the annual certificate?

No — and this is the most common misunderstanding we correct. Balances with automatic internal calibration (such as A&D's GX-A Series or GH analytical models) adjust themselves with a built-in motorised weight whenever temperature drift or elapsed time demands it. This is enormously valuable: it keeps the balance accurate between external calibrations without anyone touching it. But the internal weight is part of the instrument being checked — it cannot provide independent, traceable evidence that the balance reads correctly.

Auditors therefore expect both: internal calibration doing its silent work daily, and a periodic external calibration with traceable reference weights producing a certificate with documented uncertainty. Think of internal calibration as maintenance and external calibration as evidence.

Daily checks between calibrations

An annual certificate proves the balance was right on one day. Routine checks prove it stayed right on the other 364. The standard pattern for GMP and accredited laboratories: a documented daily or weekly check with one or two calibrated check weights — typically one near the working load — recorded in a logbook or LIMS against a defined tolerance band, with a clear escalation rule when a check fails. The check weights themselves need periodic calibration, but a working-standard class is sufficient; they do not need to match the reference class used by the calibration laboratory.

Set the tolerance band from what your weighing actually requires — the process tolerance — rather than from the balance specification, and the daily check becomes a genuine safeguard instead of a box-ticking exercise. When a check fails, quarantine the balance, and use the last passing check to bound the investigation window for affected results.

A&D Gulf's calibration service

A&D Gulf issues calibration certificates for all A&D Japan instruments from our JAFZA laboratory, with reference weight traceability to recognised national standards. Each certificate documents the instrument and its serial number, the reference standards used and their traceability, the test points and the results at each, and the measurement uncertainty. On-site calibration covers the whole of the UAE from our JAFZA base, and our own people in Saudi Arabia (Riyadh, Jeddah and surrounding cities) and Pakistan (Karachi, Lahore and surrounding cities) can attend sites in those regions. Elsewhere in the GCC, instruments are calibrated at the JAFZA laboratory. Same-day certificates are available for production-critical instruments.