Understanding UKAS Calibration for Weigh Pads: What You Need to Know

At MWS, we often get inquiries about UKAS calibration for weigh pads, particularly in light of recent updates to the industry standards. The Vehicle Certification Agency (VCA) introduced new recommendations in 2024 that have significant implications for the calibration of weigh pads used in weighing new vans and lorries. These updates emphasise the importance of adhering to the UKAS ISO 17025 standard, marking a shift away from the previously accepted ISO 9001 standard. In this blog post, we’ll explain what this means for weigh pad calibrations and how MWS can help you meet these new requirements.

The Shift to UKAS ISO 17025: Why It Matters

The VCA’s update demonstrates the need for greater precision and traceability in vehicle weighing equipment. The move to ISO 17025, a more stringent standard compared to ISO 9001, reflects the industry’s commitment to ensuring that all measurements are accurate, reliable, and fully traceable to national or international standards. This shift is particularly important in the context of vehicle calibrations, where even minor discrepancies can have significant consequences for safety and regulatory compliance.

UKAS Calibration for Weigh Pads: What Is Allowed?

Here’s the issue – unless a company has a test rig large enough to accommodate weigh pads, UKAS calibration requires using physical test weights. For heavier loads, this becomes impractical due to the sheer weight needed for compliance. This is why for heavier loads, force calibration is the standard procedure, but it’s not UKAS-approved.

Why Isn’t Force Calibration UKAS Approved?

Force calibration, which uses force transducers or hydraulic systems to simulate loads, is not accepted by UKAS for weigh pads. Here’s why:

  • Accuracy Concerns: Force calibration can introduce inaccuracies because it doesn’t fully replicate the conditions under which weigh pads operate. Weigh pads are designed to measure the actual weight placed upon them, not simulated forces. Physical weight testing, where calibrated weights are placed directly on the weigh pads, is the only method that ensures the highest accuracy and reliability.
  • Reproducibility: Physical weight tests account for all variables, including any non-linearities or mechanical differences in the weigh pad system, which might not be captured during force calibration. This means that the results from force calibration might not be reproducible under real-world conditions.
  • Traceability: Physical weights used in calibration are traceable to national or international standards, ensuring compliance with stringent accuracy requirements. Force calibration methods lack this direct traceability, which is why they do not meet the UKAS standards.

High-Quality UKAS Approved Weigh Pads

If you require UKAS-approved weigh pads, your only option currently is to buy them pre-approved and new out of the box.

MWS supplies UKAS approved weigh pads from our trusted Italian supplier, Dini Argeo. These weigh pads are designed to meet the rigorous demands of modern vehicle weighing, offering exceptional precision and reliability. Whether you need new equipment or calibration services, MWS is here to support your operations with high quality products and expert guidance.

Conclusion

The recent shift towards the UKAS ISO 17025 standard marks a significant step forward in ensuring the accuracy and reliability of vehicle weighing equipment. At MWS, we are committed to helping our customers navigate these changes and maintain compliance with the latest standards.

If you have any questions about weigh pad calibration or our range of weigh pads, please don’t hesitate to contact us.