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
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
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 here
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
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.