Metrological characterization of a new standard, in absolute and gauge pressure modes, in the range 1 Pa to 15 000 Pa

The metrological characterization of a new standard in absolute and gauge pressure modes, in the range 1 Pa to 15 000 Pa, is described. Its effective area has been determined in gauge and absolute modes by direct comparison with a 20 cm(2) simple piston pressure balance. The relative difference in the effective area between the two modes is 1.2 x 10(-6). No significant effect has been observed between the two modes for pressures down to 5 kPa. Correction coefficients have been calculated to take into account the initial condition changes. The evaluation has also provided an estimate of repeatability and linearity at low pressure. The pressure measurement uncertainty budget for this standard is presented along with some results from the calibration of working capacitance diaphragm gauges. The estimated expanded uncertainty is 8 mPa + 2.4 x 10(-5) x p in gauge mode and 13 mPa + 2.3 x 10(-5) x p in absolute mode.