For 15 years, Withnell Sensors has delivered UKAS-accredited temperature calibration services for laboratories, manufacturing sites and other regulated industries across the UK. We have continued to invest and expand our calibration laboratory to ensure that we offer some of the best possible temperature measurement uncertainties.  Maintaining this UKAS accreditation since 2011 has meant demonstrating competency annually under the scrutiny of our UKAS audits and always adapting as requirements, facilities and technologies change. Our years of experience has shaped how we approach calibration today, and has taught us some valuable lessons that we think are worth sharing. 

1. Calibration failures are important too! 

Calibration is designed to confirm compliance — but it’s real value is often revealed when something fails. Calibration failures can occur for any number of reasons. Failures highlight the need to replace or upgrade equipment, identify any non-conforming trends and give us an insight into wider systematic failures.  If equipment has malfunctioned, infrastructure changes have been implemented, cleaning routines altered, new users introduced, or procedures have changed then this might have had an unintended impact on environmental measurements. In most regulated environments a failure at the point of calibration will trigger a formal review and non-conformance investigation. This detailed and independent review includes root cause analysis, and corrective actions. As well as presenting an opportunity to implement improvements this process helps organisations identify trends, hidden risks, and early warning signs that might have otherwise gone unnoticed. A failure serves to remind us exactly why regular calibration is essential, it acts as the ultimate ‘quality control’ check.  

2. Calibration requirements can change 

As facilities expand, introduce new equipment or increase throughput, temperature calibration requirements often change in subtle but important ways. A piece of equipment might be specifically calibrated for use in a fridge, this calibration might not be valid if that equipment is then moved to a storage unit or a freezer.  

Growth can introduce new risks: additional locations, different operating conditions, varying usage patterns or tighter regulatory expectations. Calibration strategies that remain static while facilities evolve can quickly become misaligned. Reviewing calibration in the context of the wider environment, not just individual instruments, helps ensure it continues to support compliance as operations grow. Consider calibration frequency or even a change of calibration provider if your calibration strategy is going to change.  

3. Documentation matters as much as accuracy 

Accurate calibration results are essential, but they are only part of the compliance picture. During audits, it is often the supporting documentation that comes under the closest scrutiny. Clear traceability, defined measurement uncertainties and consistent reporting formats all play a critical role in demonstrating due diligence.  

Well-structured, audit-ready documentation provides confidence, not only to auditors, but to internal teams as well. Conversely, unclear or inconsistent records can raise questions even when measurements themselves seem sound. Using an accredited calibration laboratory is the only way to demonstrate confidence in calibration results. ISO 17025 is an internationally recognised standard that mandates the information that must be included on a calibration certificate. This information should cover everything that an auditor, internal or external, requires. The quickest and easiest way to determine whether or not a calibration is accredited is to look for the UKAS logo displayed on the certificate itself.  

4. Be certain about understanding your measurement uncertainty 

Measurement uncertainty (MU) is a mandatory reporting requirement for accredited laboratories and it is an important consideration when assessing the suitability of a calibration provider. It can be a complex topic to understand from a metrology perspective, especially if trying to consider all the different components that make up the reported value.  

Measurement uncertainty will be applied to each measurement that is reported, and the consideration for the customer is the potential impact on any reported error. No measurement is perfectly exact, MU tells us how much the true value could reasonably be above or below the number we measured. It can be an important indicator of the capabilities of a calibration provider. Look for  a measurement uncertainty that is relevant to your overall specification.  

MU is one of the subjects that can remain hidden until an audit brings it into focus. Other topics that will be scrutinised in audits include calibration intervals, ownership of equipment, and definition of responsibility between internal teams or suppliers. Having clear understanding and accountability in these areas prevent audits from becoming reactive events. Taking a proactive approach allows potential issues to be addressed calmly and methodically, rather than under pressure. 

5. Consistency reduces risk over time 

Reliable calibration is built on repeatability and consistency. Using the same accredited processes, standards and supplier year after year reduces variability and builds confidence in results. Over time, this consistency becomes one of the most effective ways to minimise risk in regulated environments. 

From our experience, customers benefit most when temperature calibration and data logger calibration are treated as planned, managed processes rather than isolated events. Consistent approaches make issues easier to spot, documentation easier to manage and compliance easier to maintain – particularly in environments where scrutiny is routine. From an operational perspective, good planning can also mitigate the burden of equipment being taken out of use for calibration as well as assisting the provider with offering the best possible turnaround time.  

How You Can Make Use of Our 15 Years of Calibration Experience 

If you’re responsible for calibration in a regulated environment, these lessons will probably feel familiar. Equipment changes, facilities grow, audits approach and expectations tighten – often at the same time. The challenge isn’t just keeping calibration up to date, but making sure it continues to support compliance as everything else evolves around it. 

Our role is to help make that easier. By applying the experience gained from 15 years of UKAS-accredited temperature calibration, we support customers with dependable results, clear documentation and an approach designed to stand up to scrutiny — so calibration becomes something you can be confident in, rather than concerned about. 

If you’d like to review your current approach or need support preparing for an upcoming audit, speak to our team about our UKAS-accredited temperature data logger calibration services.