PRECISE PRESSURE CONTROL IN HYDROTHERMAL EXPERIMENTS WITH COLD-SEAL PRESSURE-VESSELS

A simple apparatus is described for precise static of dynamic pressure control in hydrothermal experiments with cold-seal vessels, and its p erformance is evaluated. The device consists of an auxiliary pressure- vessel furnace assembly, a pressure transducer, and a solid-state cont roller, configured to respond to deviations between the observed and t he desired pressure by adjusting the temperature of the auxiliary stat ion. Performance tests between 2 and 4 kbar revealed that pressure, as monitored by the transducer, could routinely be maintained to within +/- 0.3 bars of the desired value for durations of at least 16 d.