DIFFERENTIAL PRESSURE CALIBRATION AT HIGH STATIC PRESSURE -A PRACTICAL APPROACH TO OPTIMISING UNCERTAINTY

摘要

The majority of high volume sales gas metering is carried out using orifice plate systems at high static pressures. The system will include one or more differential pressure sensors that will require calibration at the working static pressure in order to maintain traceability at an acceptable uncertainty. Calibration is generally carried out using a twin-post deadweight tester, but some components of uncertainty are unique to each instrument and are difficult to assess. This paper demonstrates a practical approach to the characterisation and uncertainty analysis of a twin post deadweight tester, which was used by the author to gain the lowest accredited uncertainties in the UK. The results are shown to correlate well with exhaustive experimental measurements, which would be beyond the budget of a commercial calibration laboratory.