Sneak Peek: Withnell’s Instrument Calibration Services

UKAS Calibration
How to ensure temperature and humidity equipment precision, reliability and efficiency
UKAS Calibration
How to ensure temperature and humidity equipment precision, reliability and efficiency

Sneak Peek: Withnell’s Instrument Calibration Services

Welcome to our virtual insight into Withnell Sensors’ UKAS-accredited calibration laboratory. Serving temperature and humidity equipment needs, our decades-young laboratory has been expertly designed to accurately perform instrument calibration services.

Hidden in the Old Silk Mill in Withnell, Lancashire, our laboratory has continued to expand over the past 11 years. We transitioned from calibrating one brand, Kaye, in the earliest days to now having the capability to calibrate over 50+ brands and counting.

This means our lab has grown and so with it has our service offering. But what do you know about Withnell’s instrument calibration services?

We’re here to provide you with a sneak peek behind the scenes of our calibration laboratory, its capabilities and the reasons why so many UK businesses choose us for highly accurate, expert and UKAS-accredited calibration services!

High precision from the offset

The end goal for many of our customers when their equipment enters our lab is to have peace of mind that their instruments are performing accurately. This requires high precision from the calibration service itself.

From our audited Quality Management System to the technical capabilities of our calibration engineers, complete assurance is provided from the offset at Withnell Sensors.

Your equipment will always be in safe hands as it moves throughout our calibration lab. Let’s take a look around and see what we can find:

Behind the glass door!

The entryway to precision

From first glance, you can immediately take in our extensive range of market-leading calibration equipment, specialised software, high-precision reference standards and various temperature and humidity instruments all undergoing calibration.

Along the right-hand side of our main lab space, you will see our custom Kaye IRTD calibration set up. Specifically designed to replicate the manufacturers recommended calibration process ranging from -196°C up to 420°C utilising a mix of comparison baths and primary standard, fixed-points. A fixed-point calibration provides the most accurate calibration possible.

Our trained technicians have experience calibrating a range of brands, well-versed in all of the brands we offer to our customers, including our LogTag, Vaisala, SenseAnywhere and Elitech data loggers, as well as a range of other well-known products on the market.

The technicians have undergone extensive training to enable them to perform calibrations, working with measurement uncertainties from as low as 5mK. We also maintain an onsite supply of liquid nitrogen to ensure our technicians can calibrate cryogenic equipment accurately and predictably when required by our customers.

Within this laboratory space you will also find multiple, high precision, calibration baths. Allowing for comparison calibrations, these baths still deliver impressive uncertainties due to their extensive validation and our unique calibration temperature reference for each individual bath. We offer any mix of calibration points from -90°C to 250 °C with our best measurement capability being from 11mK.

UKAS calibrations with ISO17025 quality assurance

Our in-house Quality team proudly maintain our accredited quality management system to comply with the key QMS areas such as document and record control, Non-conformances, CAPA and internal audits.

In most cases, our customers request a pre-emptive calibration after a set period, as determined by their own internal quality control measures, our most popular interval being annually, however, our quality team are available to support customers with their individual requirements.

Of course, all of our calibration labs are environmentally controlled. This is a fundamental part of ensuring the consistency and repeatability of our measurements as well as minimising the impact on measurement uncertainties. You can read more about measurement uncertainty in our blog post here.


You will also find a dedicated space for the calibration of the Kaye AVS and the Kaye Validator, here locates our specialist, controlled test equipment. Although the Kaye equipment is regularly used for the measurement of temperature, the calibration parameter here is actually voltage.

Due to the critical nature of the environments in which the AVS is used, such as GMP temperature mapping and autoclave validations, the AVS must be routinely calibrated and serviced. Any inaccuracies in the Kaye AVS can lead to errors in validations which can ultimately affect regulatory compliance and product quality and safety in the pharmaceutical sector.

Our team has been trained directly by the manufacturer and has direct access to parts for critical repairs and refurbs. This ensures that equipment calibrations are completed effectively and efficiently.

We continually invest in our laboratories and maintain the most accurate test equipment; this enables us to provide measurement uncertainties as low as 1 microvolt.

Expansive space for quick turnaround times

Our PRT calibrations offer reassurance that your own results are accurate and in line with your own temperature standard. Through a combination of fixed points and fluid comparison baths, this instrument calibration service can range from -196°C to 420°C.

Fixed point cells contain materials with a clearly defined and obvious phase transition, such as the freezing point of zinc. We deploy these fixed points to serve as primary standards whereby the cell is brought to its equilibrium state at a given temperature and is then referenced against a sensor or instrument. They’re suitable for various scientific, industrial, and regulatory applications so you’ll see them pinpointed throughout the lab.

Our internal range of equipment is of high specification and includes our own Thunder Scientific chambers, which are best in class for humidity calibrations. This helps us to provide calibrations across the range of 10 to 90%rh and 10°C to 60°C.

This, along with the many other instrument calibration services we offer, is suitable for routine monitoring of the cold chain, controlled storage of products and goods, documented preventative maintenance processes and much more.

By continuing to expand our calibration laboratory in accordance with the variety of process measurement equipment available in today’s market, we can accommodate fast, responsive turnaround times ranging from 5 to 7 days (express) or 2 to 3 weeks.

We also offer on-site calibration services

While talking about our portfolio of calibration services, we must also mention our trips outside of our laboratories. On-site calibrations can be completed at our customer's premises too.

This includes fridge, freezer and chamber calibrations where we identify the difference between the displayed values of the enclosure and the corresponding values measured.

Here our technicians will work through the preparation and stabilisation of the environmental chamber (or similar) in order to verify and adjust their settings accordingly. We deploy different calibrated temperature sensors at various locations within and around the chamber. Pain spots always include near the door, at the top, middle and bottom of the shelving and near the cooling unit.

From here we can collect the relevant measurement data, assess and verify before producing the compliant documentation of all calibration activities.

If you’d like a humidity calibration service included, depending on the chamber, then we offer a traceable service by utilising temperature and humidity sensors such as the Vaisala loggers, and calibrate against high precision reference standards such as our chilled-mirror hygrometers.

If your annual calibration due date is right around the corner, get in touch with us to discuss your measurement range requirements and we’ll deliver an expert, UKAS accredited instrument calibration service at an unmatched price point.