DM 1000 is designed for accurate PVT measurement for gases. Based on the state of the art Burnett technique, it helps users to obtain PVT data accurately and automatically:

★ temperature measurement uncertainty: better than ±5mK (DM1020);

★ pressure measurement uncertainty: better than ±2kPa (DM1020);

★ wide temperature range: -30℃~120℃;

★ Wide pressure range: 0~13.8MPa;

★ various properties: PVT data, virial coefficients, and virial equation of state (EOS);

★ highly automatically: automatic temperature control system, automatic temperature measurement system, automatic pressure measurement system, automatic data acquisition and automatic data analysis.

The performance of DM1020 was checked by measuring the PVT of gaseous dimethyl ether (DME) in the temperature range of 298~353 K and pressure range from 74~2040 kPa. Figure 1 shows the experimental data.

Figure 1 experimental PVT data of gaseous DME

According to the calibration of instrument constant, the second and third Virial coefficients were obtained and listed in table 1.

Table 1 Virial coefficients of DME

From the second and third virial coefficients, the viral EOS of gaseous DME was expressed as:

The MAD and MMD between experimental pressure and calculated pressure from equation with temperature and gas density are 0.10% and 0.40%,respectively; while the MAD and MMD between experimental density and calculated density from equation with temperature and pressure are 0.11% and 0.49%,respectively. Deviations are showed in Figure 2 and Figure 3.