Air gauge back-pressure uncertainty estimation for the advanced test rig

In the paper, the uncertainty estimation of the back-pressure measurement in the advanced experimental rig equipped with the electronic devices, pressure transducers, precise step motors is discussed. The proposed apparatus was used in case of some accurate and dedicated applications that required experimental examination of the selected air gauges to confirm their capability. The advanced experimental rig for the air gauges properties assessment is a system consisting of many elements, each of them adding some uncertainty to the final measurement result. The main sources of uncertainty are identified as following: operator, environment, mechanical unit, electronic unit, pneumatic unit, data processing. Assessment of the back-pressure uncertainty was performed using the method A. The series of repetitions revealed that the uncertainty of the back-pressure indication depends on characteristics (measuring range and sensitivity) of the actually examined air gauge. Additional attention was paid to the flow instability in the measuring chamber that causes the instability of the back-pressure measurement results.