Studies on the Stability of the Industrial Pressure Balances for Hydrostatic Pressure Measurement up to 100 MPa

In the present paper, the results on the study, carried out on industrial pressure balance (PB) have been reported, which was characterized at NPL twice. The results thus obtained are also compared with the values reported by the manufacturer at the time of procurement and the stability of the effective area is established for the last seven years. Further studies were carried out on the same type and model of PBs as previous PB, being used by different users at two different locations. It is observed that there is a small change in the short term stability but the change is prominent in case of long term stability. However, such changes are well within the estimated measurement uncertainty of the instrument. The change in effective area is quite significant for the identical models at three different locations in India i.e. in Delhi (north), Chennai (south) and Guwahati (west), due to obvious reasons of different form geometry of the p–c assemblies. However, the behavior of effective area is found similar at all the three locations. The causes for such behaviours are described.