High pressure thermal expansion of gases: measurements and calibration

A set-up based on transitiometric principles has been designed for direct measurements of high pressure cubic expansion coefficient of gases. A new method of calibration was presented for pressure-controlled calorimeters working with open mass calorimetric vessels. The new method is based on heat capacity standards and thus is a complementary to the previous methods based on thermal expansion standards. The calibrations performed with the new method using a number of heat capacity standards demonstrated that the calibration constant of correctly designed calorimetric vessels does not depend on pressure. The results of test measurements with nitrogen performed accordingly to the thermodynamic foundations of the method are in satisfactory agreement with the literature data.