System for controlling liquid or vapour pressure in buffer vessel - uses electronic comparator and three=way membrane valve

摘要

The pressure control system comprises a buffer vessel (1) whose internal pressure is to be maintained at a level that can at any time be adjusted by setting a calibrated dial in a pressetting unit (8) which is applied to a comparator (7). A pressure transducer (5) produces an electric current which is amplified (6) and applied to the said comparator (7). The same controls a threeway valve (3) with the result that the vessel (1) is either connected with a higher pressure source (Pso) or with a lower pressure source or bleed-off line. Based on the membrane valve capacity for quick response, the postulated pressure level can be well maintained. ADVANTAGE - Tecnhique is applicable to small and large vessels alike.