Equipment requirements in ISO/IEC 17025 (clause 6.4)

Clause 6.4 is the equipment clause. It covers measuring instruments, software, reference standards, reference materials and consumables. Equipment must be verified to meet requirements before being placed into service, and a calibration programme must be established and reviewed to maintain confidence in calibration status.

Records the clause asks for

• Identity of the item and its software/firmware version.
• Manufacturer, model, serial number or other unique identifier.
• Evidence of verification that it meets requirements.
• Current location.
• Calibration dates, results, acceptance criteria and the date the next calibration is due (or the interval).
• Reference-material documentation.
• Maintenance plan and maintenance performed.
• Damage, malfunction, modification or repair.

When equipment is found out of tolerance, the laboratory must examine the effect on previous results and apply nonconforming-work procedures where needed.

Fit for purpose is a decision, and it has to be recorded

Clause 6.4.4 requires equipment to be verified as conforming to specified requirements before being placed or returned into service. That is not the same as unpacking it and checking it powers on. The specified requirements come from the method and the uncertainty budget: if the budget assumes a readout contributing 0.003 °C, verification means establishing that this readout does, not that the brochure says so.

The same applies on return from repair or recalibration. An instrument comes back adjusted, and the budget built on its previous behaviour no longer describes it. Reading the certificate before the instrument goes back on the bench is the control, and skipping it is how an out-of-tolerance finding stays undetected for a full interval.

Intermediate checks, which the clause requires and most laboratories skip

Clause 6.4.10 says that when intermediate checks are necessary to maintain confidence in performance, they must be carried out according to a procedure. For a reference thermometer calibrated annually, the honest question is what happens if it drifts in month three: without a check, every certificate for nine months is at risk, and a discovery at recalibration triggers clause 7.10 across all of them.

Trend the results rather than filing them. A single ice-point reading proves very little; twelve of them plotted show drift long before the annual certificate does, and that chart is also the evidence for setting the interval under 6.4.7.

Software and firmware count as equipment

• The version is a required record under 6.4.13. A result cannot be tied to the calculation that produced it otherwise.
• A firmware update is a change to a verified item, and requires verification that it still meets requirements — including that stored coefficients survived the update.
• Equipment must be safeguarded from adjustments that would invalidate results (6.4.7): password-protected calibration menus, seals, or controlled access to coefficient entry.
• Spreadsheets used for calculation are in scope too, with version control and formula verification.

When equipment is found out of tolerance, clause 6.4.9 requires it to be taken out of service, labelled, and the effect on previous results examined. The look-back is the obligation people forget, and it is the one that costs the most when it is done late.