Uncertainty Modelling of the Reference Pressure Generating with OIML and ASTM Weights in Pressure Balances

A pressure balance is a combined with a piston-cylinder unit and a system for the application of a vertical load on the piston. Pressure balances are primary measuring systems those measure pressure in terms of force per unit area. Reference pressure can be generated by a pressure balance. There are many parameters to calculate reference pressure, such as piston’s area, linear deformation of piston and cylinder, measuring temperature, mass, local gravity, surface tension of measuring liquid… All of these parameters have got measurement uncertainty, effects of these uncertainty components must be added to the uncertainty budget of reference pressure. In this study, the uncertainty model function of reference pressure is derived. And the uncertainty model function is rearranged. If the masses of pressure balance are calibrated according to the OIML R-111 or ASTM E-617 guides, the uncertainty model function that is given in the study can be used directly to calculate uncertainty of reference pressure.