High pressure measurement with simple piston gauge in static condition

This paper describes the characterization of the newly developed piston gauge pressure standard at the National Physical Laboratory (NPL), with particular reference to its fall rate, engagement length of the piston and the deceleration rate for the measurement of hydraulic hydrostatic pressure up to 60 MPa. The low pressure effective area of the gauge derived from its dimensional measurements when compared with the value obtained by its direct calibration against NPL transfer pressure standard agrees within 0.025%. The pressure gauge is quite stable, reproducible and has a sensitivity of 3 ppm. Though the theoretically calculated value of the pressure coefficient is low as compared to the experimentally observed one in its absolute terms, the pressure dependent effective area agrees within ± 0.025% over whole of the pressure range which is well within the uncertainty statement of the two independent techniques used.