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WIKA is a manufacturer of measuring instruments whose technical publications describe pressure measurements using elastic sensing elements. Its technical information distinguishes pressure-driven deformation from the linkage and pointer mechanism that turns it into a measurement indication.^[ref] Its documentation is useful for connecting a physical measurement principle to the specifications of a complete instrument.

A concrete specification also illustrates the difference between an error limit and measurement uncertainty. WIKA's June2025 US sheet for specified four- and six-inch gauges gives a base limit of $\pm 1.0\%$ of span and an additional temperature error of $\pm 0.4\%$ of span per $10\mathrm{K}$ away from the $20{}^{\circ }\mathrm{C}$ reference.^[ref]

For an original instrument example with span $1\mathrm{MPa}$, the base bound is $10\mathrm{kPa}$. A $20\mathrm{K}$ temperature departure contributes a further bound $8\mathrm{kPa}$. Adding those magnitudes gives a conservative $18\mathrm{kPa}$ combined bound under this simplified interpretation; it is not a statistical root-sum-square uncertainty calculation. At a reading of $100\mathrm{kPa}$, even the base bound is $10\%$ of the reading, despite being $1\%$ of span.

The example concerns the stated version and conditions, not a brand-wide accuracy claim. Use the actual model, range and pressure gauge temperature error specification together with instrument calibration evidence when interpreting a particular Bourdon tube pressure gauge.