Direct answer
Check five hard criteria in order: whether the scope of accreditation covers your specific item, whether the key equipment is in-house, whether your sample dimensions are within equipment capability, whether the report will be accepted by your customer or regulator, and whether anomalous data is reported proactively. Price comes after these five — one re-run usually costs more than the difference.
Five hard criteria
One: the scope of accreditation, not the certificate cover
Ask for the annex to the scope of accreditation and check it item by item. The certificate proves the body is qualified; the annex proves it can run your item. The two are constantly conflated.
Two: how much of the key equipment is in-house
Ask one question: "on which site and which machine will this item be run?" Subcontracting is not a problem in itself, but it makes scheduling uncontrollable and blurs the boundary of responsibility. At the very least it should be disclosed in advance.
Three: the limits of equipment capability
Sample dimensions, weight and the upper end of the range. Items beyond those limits are either refused or run with compromised conditions. Checking in advance is cheaper than re-working afterwards.
Four: acceptability of the report
Who will read the report? Domestic regulatory work and tendering require CMA; export and foreign-invested customers put more weight on CNAS; some industry customers only accept reports from designated bodies. Confirm the recipient's requirement first, then choose the laboratory.
Five: how anomalous data is handled
When a test fails or the data looks anomalous, does the laboratory record it honestly and tell you, or "adjust until it passes"? This is hard to ask directly at the quotation stage, but you can read it from two side signals: whether they are willing to have you witness the test, and whether the report records the test conditions and any deviations in full.
Three things to understand in the quotation
- Whether the items map one to one onto the standard: omitting items is a common way to compete on price, and you only find out at acceptance
- Sample quantity and number of runs: some items require several samples and take the worst case, while the quotation counts only one
- Whether re-testing is included: ask up front how a re-test after a failed first run is charged
Three warning signs
- Cannot state a specific standard number and revision, only "we test to the national standard"
- Cannot provide the annex to the scope of accreditation, or avoids the question
- Asks nothing at all about sample state, operating mode or mounting location
The third is the most telling. An engineer who has really run this type of project will ask you a pile of conditions first — without them, the plan cannot be fixed.
Where price belongs
Price matters, of course, but it belongs after the five hard criteria. The reason is simple: the time cost of one re-run, the sample cost and the cost to customer trust usually exceed the spread between quotations.
The sensible approach is to shortlist two or three laboratories against the five criteria, then compare price among those.
Where we stand
TMC LAB holds both CMA and CNAS accreditation, with a laboratory of roughly 10,000 m² and over 500 sets of equipment. All testing is performed in our own laboratory with no subcontracting, and site visits plus witness testing are available. If you need to verify the scope of accreditation, ask us for the annex directly.
Related pages for this question
Last updated Technical criteria follow the current standards and the agreed scope; please confirm the specific project with the lab.
