499.    ----------------.[CHAUX, R.]  Sensitive Pressure Controller in Hydrocarbon Synthesis.  Vol. 63, 1950, pp. 59-60.

                 Very efficient sensitive pressure controller is described.  The basic principle of the device is the well-known use of a ball valve held on its seating by a tension spring.  It is at present operating on a fluid bed, Fischer-Tropsch process, and maintains a constant 20 atm. pressure at gas-flow rates of 2 to 60 cu. ft. per hr.  It is capable of maintaining a preselected pressure for indefinite periods without supervision.  The control limits can be broadened by changing the tension of the spring.