Establishment of High Pressure Pneumatic Standard up to 40 MPa at NPLI

The current paper describes the successful establishment of high pressure pneumatic secondary standard for the realization of national pneumatic pressure scale up to 40 MPa from the previously existing 12 MPa. The traceability as well as the uncertainty in measurement was established through a continuous chain of measurements from very low pressures starting with the ultrasonic interferometer manometer and successive extension in overlapping pressure ranges. For this purpose a piston cylinder assembly designated as NPLI-40, with a pressure range of 0.2–40 MPa was coupled to a mechanical gas booster through a high gas pressure controller. We have experimentally estimated the zero pressure effective area of piston as well as the distortion coefficient which is traceable to the international system of unit SI. The CMC for the same is now on the BIPM website. The results obtained are discussed in detail.