Understanding accredited testing.

No, and it would not for any laboratory. Accreditation is issued for the specific methods and locations on our schedule. We will tell you, test by test, what is accredited for your project and what is not.

An accredited result has been produced under a quality system that UKAS has independently assessed for that method, including equipment calibration, staff competence and reporting. A non-accredited result may be technically sound but has not been assessed in that way, and the report must say so.

Usually not. There are in-situ, laboratory and derived CBR approaches and they are not interchangeable. Send us the full specification or tell us what the result is for, and we will confirm the appropriate method and its accreditation status.

Where a project needs a test we do not hold in scope, we will say so and, where appropriate, arrange it through an accredited partner laboratory with the reporting agreed in advance.

Search the UKAS website for the laboratory name or number and open its schedule. Hixtra's UKAS testing laboratory number is 8996.

UKAS is the United Kingdom's sole national accreditation body, recognised by government to assess whether testing, calibration, inspection and certification bodies are competent to do what they claim. ISO/IEC 17025 is the standard it assesses testing laboratories against. It sets requirements for staff competence, equipment calibration and traceability, validated methods, handling of samples, evaluation of measurement uncertainty and how results are reported and reviewed before release.

It lists, line by line, the materials or products the laboratory is accredited to test, the type of test or property measured and the standard or method used, with a location code showing where that work may be carried out. Each schedule carries the accreditation number, an issue number and an issue date, so you can tell which version you are reading. If the method your specification names is not on the list, it is not accredited.

They mean the laboratory holds accreditation under that number, and that the results on the report fall within its accredited scope unless the report says otherwise. The symbol is not a blanket endorsement: where a report also carries results from a method outside the schedule, those results have to be clearly identified as not UKAS accredited. The check is therefore result by result, not laboratory by laboratory.

On-site testing can be accredited. A schedule of accreditation carries a location code against each entry, and where a laboratory is accredited for work away from its own premises the schedule shows that in a separate section for site activities. It does not follow automatically, though: a laboratory can hold a method in scope in its permanent laboratory but not on site, or the other way round. Check the location as well as the method.

Go back to whoever wrote the specification and get the test methods named, because accreditation is granted against specific methods and the phrase on its own cannot be checked. Without a method there is nothing to look up on a schedule, and two laboratories can both be UKAS accredited while neither holds the test you actually need. Tell us what the result is for and we can suggest the methods that normally apply, so they can be written in.

Yes, because sampling is a separate activity from testing and can sit inside or outside an accredited scope. Where sampling is within scope it is covered alongside the test. Where a sample arrives from site taken by someone else, the results apply to the sample as received and the report will say so, which matters if anyone later questions whether the sample represented the material. Ask us which stages of your programme are covered.

Measurement uncertainty is the range within which the true value is expected to lie, given the method, the equipment and the way the test was carried out. No measurement is exact, and an accredited laboratory has to evaluate it. Under ISO/IEC 17025 it is reported where it is relevant to how the result will be used, where you ask for it or where it affects whether the result meets a specification limit.

UKAS accreditation is about technical competence to carry out named test methods, whereas CHAS and SSIP are health and safety pre-qualification and AGS is a trade association. Accreditation involves an independent assessment against ISO/IEC 17025, covering equipment, methods, staff and reporting. CHAS and SSIP confirm that a contractor's safety arrangements have been assessed. Hixtra carries all four, but only the UKAS accreditation says anything about the validity of a test result.