Improvements in and relating to chemical process emergency shut-down systems

摘要

894,282. Electric selective signalling systems. IMPERIAL CHEMICAL INDUSTRIES Ltd. Aug. 12, 1960 [Aug. 24, 1959], No. 28912/59. Class 40 (1). A chemical process emergency shut-down system which is operable by a fault-indicating signal from any one of a number of signal sources, includes an indicator comprising a plurality of cold-cathode discharge tubes 2, each associated with a respective signal source 1 and connected in parallel across supply terminals 6, 10, resistors 5, 8 being chosen so that when the output of a source exceeds a predetermined limit, the associated tube 2 is fired and the voltage applied to the assembly of tubes 2 falls below the value required for the remaining tubes to be fired by their respective signal sources. In this way an indication of the origin of a fault is obtained even though a succession of further fault-indicating-signals and corresponding shutdown operations may follow the original fault. Tubes 2 may be replaced by relays which operate lamps or bells.