Long-term evaluation of effective area ratio of pressure balances

A pressure balance is a device that is implemented directly from the basis of the definition of pressure and can be used as a pressure standard. Its main components are a piston-cylinder assembly and weights. The force generated under the weight whose mass has been measured precisely is exerted on the piston. When the pressure is applied to float the piston under load up to the equilibrium level, this pressure is defined by dividing the force by the effective area of the piston-cylinder assembly. The most important factor in determining the precise pressure generated by the pressure balance is the effective area. Comparative measurement of reference and test pressure balances using the cross-float method is widely used to calibrate the unknown pressure generated by the test pressure balance. From the measurement results, the effective area ratio of the two pressure balances is obtained. We have evaluated effective area ratios of two pressure balances in various combinations on a regular and systematic basis. In this article, some typical examples are given.