A discussion of methods for the estimation of volumetric ratios determinedby multiple expansions

The volumetric ratios form a critical component in the characterisation of static expansion systems and periodic re-determination of the ratios is req uired. In order to avoid disassembly of the system an in-situ procedure is used. Simple explicit equations for the volumetric ratio may only be derive d under isothermal conditions, a situation not often encountered under expe rimental conditions. Methods to account for the temperature gradient betwee n the vessels and the drift in the vessel temperature during the experiment have been developed and are presented. (C) 1999 The National Physical Labo ratory. Published by Elsevier Science Ltd. All rights reserved.