Product Testing Services
The Product Testing Services domain covers laboratory work under ISO/IEC 17025:2017. The exam tests method selection and validation, metrological traceability, measurement uncertainty, quality control, and reporting-especially statements of conformity, where decision rules change the answer.
Methods and validity
- Selection (7.2): use the client-specified method, the published standard method, or a documented in-house method.
- Verification: confirm the laboratory can properly perform a standard method before first use.
- Validation: required for non-standard, modified, or out-of-scope methods; keep records of the validation evidence.
- Ongoing quality control (7.7): certified reference materials, replicates, blanks, proficiency testing, and interlaboratory comparisons.
Traceability and uncertainty
Metrological traceability (6.5) requires an unbroken calibration chain to SI units, typically through accredited calibration or certified reference materials. Measurement uncertainty (7.6) must be estimated for each measurement and reported where the method, customer, or conformity statement requires it.
Statements of conformity (7.8.6)
A conformity statement needs an agreed decision rule. Simple acceptance compares the result directly with the limit; guard-banded acceptance accounts for uncertainty. The rule and its risk must be stated on the report.
Worked example
A tensile test requires a breaking load of at least 10.0 kN. The measured result is 10.2 kN with expanded uncertainty U = 0.4 kN (k = 2). Under simple acceptance, 10.2 ≥ 10.0, so the item conforms. Under a guard-banded rule that accepts only when result − U ≥ limit, 9.8 ≥ 10.0 is false, so conformity cannot be declared. The report must name the rule used, because the same data produce different verdicts.
Traps that cost marks
- Calling a verified standard method “validated”; validation applies to non-standard or modified methods.
- Reporting pass/fail without stating the decision rule and uncertainty basis.
- Omitting uncertainty where it affects conformity.
- Concealing subcontracted or non-accredited results instead of flagging them (7.8.2.1).
- Relying on expired calibration or missing traceability records.