Calibration: Testing times for instrument accuracy

Andrew Simpson

Accurate measurement is the base factor in all industrial processes and testing systems and is essential for the delivery of high-quality products and services. The calibration of test and measuring instrumentation is therefore vital to ensure that equipment continues to meet its published performance specification. 

Calibration provides the means by which instrument operators are given the assurance that their equipment is measuring correctly and that the performance of products and processes evaluated using the equipment can be trusted. Businesses that are ISO 9001:2015 accredited must also have a traceable record of calibration for finished products and as a result a company’s quality manual should therefore typically determine the calibration requirements of different instrumentation.

In addition, an original equipment manufacturer will usually also provide calibration recommendations or a trade association might provide advice for a particular industry, application or measurement function. However, what is suitable calibration for one type of equipment may not be the same for another and a different calibration service may be required for instrumentation used in different test and measurement applications.

For example, in some cases a simple function or confidence check may be sufficient for certain applications. In others a comparison to the original specification will be required, and any necessary adjustments carried out to rectify ‘out of specification’ performance. Calibration may also need to be tailored to a company’s specific requirements with testing at specific points more suitable for the application.

If any faults are found during calibration, they may need to be repaired as the precursor to re-calibration, or simply be reported and the instrument returned. If variations from specification or agreed values are discovered during testing, calibration certificates should show ‘as received’ and ‘post adjustment’ measurement values, as well as details of measuring limits or tolerances.

In addition, another factor may be where the calibration work is carried out, with the availability of ‘mobile calibration personnel’ meaning that indispensable instrumentation no longer has to be sent away to be calibrated. As a result, downtimes for vital test equipment can be minimised and the risk of damage to instruments during transit removed, whilst high standards of workmanship‚ technical expertise and accuracy are still maintained.

For these reasons, calibration facilities must offer a certain amount of flexibility to ensure different levels of service are available to meet the range of calibration needs, and industry requirements.

ISO/IEC 17025:2017 is the standard for which laboratories must hold accreditation in order to be deemed technically competent. In many cases, suppliers and regulatory authorities will not accept test or calibration results from a lab that does not have this accreditation. In the UK, UKAS is the national body recognised by government for the accreditation of calibration and testing laboratories. UKAS accreditation confirms the technical competency, impartiality and reliability of a calibration provider to deliver accurate results and authorises laboratories to issue ISO17025 accredited certificates.

Regular UKAS assessments ensure that test procedures, the equipment used and the technical capabilities of test staff are of the highest standards, with assured traceability to national, or in some cases, international standards. From an accountability perspective, many businesses require the UKAS endorsement in order to maintain compliance with their own regulatory authorities and standards bodies.

Some calibration services may not be accredited to ISO17025:2017, but still be certified to ISO 9001:2015. Although such laboratories can provide traceable calibration, this is a generic standard for quality management systems and does not necessarily demonstrate technical competence to produce valid and accurate data measurement.

In the interests of meeting the needs of all customers and instrumentation types, accredited laboratories can offer both levels of service to meet specific requirements. Nevertheless, the requirement for calibration certification from an accredited or non-accredited source will largely be determined by individual requirements, depending on the level of assurance the equipment’s output reflects on the processes and products of the user/company.

Choosing a service

Those companies that provide an accredited service themselves such as product testing and standards compliance, or are involved in an application that requires greater confidence in the reliability of instrumentation such as electromedical equipment, are more likely to require calibration in ISO17025 accredited laboratories.

Quality assessors may consider that a non-accredited calibration is inadequate, but the broader decision is essentially one of risk management; how important is it that your goods and services are based on measurements taken with fully assessed and correctly calibrated equipment? Can you afford the risk to your market reputation caused by unreliable results?

Careful consideration is essential in choosing the right calibration service for your equipment needs. Not only to ensure value for money but, more importantly, to ensure the technical integrity and continued fitness for purpose of your instrumentation. Calibrationhouse, which is accredited to both ISO9001 and ISO17025‚ has a track record of working with leading test instrumentation brands Fluke, Seaward, Megger, Keysight, Agilent, and specialist electromedical equipment suppliers such as Rigel, Fluke Biomedical, B.C Group, Pronk Technologies and others.

The importance of accurate calibration of all instruments cannot be underestimated in ensuring that equipment continues to provide an acceptably reassuring service. Any lack of control or knowledge within the calibration arena not only has a consequent adverse effect on the quality of service provided, but could ultimately lead to a failure to meet regulatory requirements including health and safety regulations. Ultimately, planned and effective calibration ensures long term accuracy, standardisation and repeatability in measurements, providing reliable benchmarks and results, and delivering successful test programmes today and long into the future.

The company has invested in a wide range of calibration equipment, facilities and an on-site calibration team to offer a broad range of services. Customers already recognise the quality and expertise provided, adding even more value to current operations through authoritative, trustworthy and rapid services that ensure their own compliance programmes aren’t compromised.