 The National Physical Laboratory (NPL) is the UK's national measurement institute and is a world-leading centre of excellence in the development and application of the most accurate measurement standards, science, and technology.
The project
NPL wanted to reduce the uncertainty in the calibration and further use of the hydraulic force standard machines located in its new state‑of‑the‑art building in Teddington. This machine characterisation work required the development of a novel force-measuring system with the appropriate capacity and accuracy.
NPL was considering an in‑house design and manufacture of this type of system, but discussions with Flintec resulted in investigations into whether commercially-available transducers could be used and provide the required performance, while also being a more economic solution.
The solution
Flintec designed a modular build-up system based on their RC3 50T load cells for use as a compression force transfer standard. The design allowed for the use of individual load cells, in three groups of three loaded in parallel, to fit the space envelope provided within the NPL 5 MN hydraulic force standard machine (450 mm square by approximately 1 000 mm high).
NPL performed extensive testing on the RC3 50T load cell type used, collaborated on the design of the system with Flintec, and is presently writing the software needed to commission and use the system.
The final solution was a bespoke "design, develop, and manufacture" project with an output of a single system consisting of nine off RC3 50T load cells and all necessary mechanical hardware.
The system is designed to withstand an operating period of 40 hours uninterrupted use per week for five years. If its long‑term performance is suitable, it could also form the basis of a new national force standard, replacing the 5 MN machine itself.
The result
NPL are currently commissioning the system and evaluating its performance. Its scientists are confident that the uncertainty in the forces generated by the 5 MN machine (or, at the very least, the effort involved in determining this uncertainty) will be reduced.
The NPL scientists involved in the project have been impressed by Flintec's design capabilities, quality of manufacture, and customer support. It is hoped that this will lead to further collaborative work between the two organisations.
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