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What is Calibration?

Calibration basically involves the comparison of a measuring instrument, the Unit Under Test (UUT) to a Standard of known accuracy. The standard would ideally be more accurate than the UUT and have its own calibration certificate which can be traced back through an unbroken chain of calibrated standards to an appropriate standard held by a National Laboratory. In the UK, this would be the National Physical Laboratory (NPL).

What is UKAS?

UKAS Calibration is calibration undertaken by a laboratory, which has been independently audited and subsequently accredited to carry out the work. UKAS (United Kingdom Accreditation Service) is the sole body recognised by HM Government for assessing and accrediting the competence of calibration and testing laboratories.

UKAS Accreditation, ISO/IEC17025

Laboratories are accredited by UKAS to the British Standard ISO/IEC 17025: 2005 which is the internationally recognised standard for the competence of calibration and testing laboratories.

Our own systems, people, their training, and our technical capabilities are thoroughly examined and tested each year by a team of UKAS auditors, each of them specialists in their field. It is an expensive and time consuming process, but our ongoing accreditation and fulfilment of the requirements of ISO17025 means that you can rest assured that we have the competence, impartiality and performance capability necessary to consistently deliver technically valid calibration results each and every time.

Accreditation to ISO17025 also means our quality management systems meet the principles of ISO9001. This is endorsed by three major international organisations' the International Organisation for Standardisation (ISO), the International Laboratory Accreditation Co-operation (ILAC), and the International Accreditation Forum (IAF). We also hold accreditation to ISO9001 from BSI, which means our Quality Management Systems are also examined on an annual basis.

Certification of a laboratory to ISO9001 alone relates only to the laboratory's Quality Management Systems, not the technical competence of the laboratory.

Our UKAS Certificate of Accreditation can be downloaded from our website

It is important to note however that UKAS accreditation of a calibration laboratory does not necessarily mean that the laboratory can issue UKAS certificates for everything that it calibrates.  Each individual calibration technique has to be separately accredited. The laboratory's 'UKAS Schedule of Accreditation' will detail the activities for which they have been accredited.

Our UKAS Schedule of Accreditation can be downloaded via
www.ukas.com and follow the links to Calibration/Lab Search/Lab No 0125.

If you are unsure whether we or any other laboratory are UKAS accredited to carry out a particular calibration you can check the Schedule of Accreditation via the UKAS website
www.ukas.com and follow the links as above.

UKAS Calibration Certificates

A UKAS Calibration Certificate should be instantly recognisable by the UKAS Accreditation Symbol depicting the Royal Crown, which is printed in the top right hand corner of the front page. The certificate should detail the measured results of the calibration, both before and after any adjustments if this is appropriate. It should also detail the uncertainty that is associated with the reported results.

It is not however, possible to obtain a UKAS calibration certificate for every conceivable piece of measuring equipment. There are instances, where for some types of instrument, no laboratory has been accredited.

Or it may be a UKAS Accredited laboratory has additional capabilities, which have not been UKAS accredited. A 'Traceceable', 'In-House' or "Class 1" Calibration Certificate (they're all the same thing) would usually be offered in these circumstances.  Whilst not bearing the UKAS symbol with Royal Crown, this certificate should, at the very least, detail the measured results of the calibration and the associated uncertainty of measurement.

Unfortunately many manufacturers 'calibration certificates' supplied with new instruments do not meet any of the above requirements. This makes them no more than 'Certificates of Conformity' rather than true calibration certificates. These would not normally be acceptable to an auditor.

We hope you have found this document useful and invite you to contact us if you require any further information or assistance with your calibration requirements.