ISOCHORIC (P,RHO,T) MEASUREMENTS FOR 5 NATURAL-GAS MIXTURES FROM T = (225 TO 350) K AT PRESSURES TO 35 MPA

Measurements of the (p, rho, T) properties of five natural gas mixture s were carried out at temperatures from (225 to 350) K at pressures to 35 MPa using an isochoric gas expansion apparatus. Ten isochores have been determined for each mixture at densities ranging from 1 mol . dm (-3) to 16 mol . dm(-3). The gas samples were prepared gravimetrically from pure gases of verified research-grade purity. The uncertainty of the density measurements arises primarily from uncertainties involved in the determination of the experimental cell volume and of the amoun t of substance contained in the experimental volume. When all componen ts of experimental uncertainty arising from random effects are conside red, the expanded uncertainty (comprising 95 per cent confidence inter val) of the density measurements is estimated to be 0.044 per cent. (C ) 1997 Academic Press Limited.