Uncertainty of Sine Input Calibration Apparatus for the Air Gauges

摘要

In the paper, dynamic calibration of air gauges with small chambers is discussed. Proposed sine input test rig is described, and its uncertainty is evaluated. Three main sources of uncertainty are identified as a Mechanical Unit, Pneumatic Unit and Digital Unit. Type B uncertainty estimation is considered, and the most difficult to assess sources are pointed out. Namely, it is the fluctuation of the back-pressure due to the airflow inside the air gauge. Thus, it was proposed to estimate the Type A uncertainty through the repetitions of the time constant measurement. The results provided highly satisfactory level of expanded uncertainty ca. 0.001 s. This result is covering all factors of influence on the dynamic calibration result.