Malfunction of process instruments and its detection using a process control computer

From an initial concern with investigation of ways in which the process control computer could learn the project was narrowed down to instrument malfunction detection. Preliminary surveys in industry were made and from there general ideas of modes of failure of some instruments were obtained. A wider survey of instruments in different environmental conditions followed. Failure information and reliability data on about 9,500 instruments representing a total of about 4,500 instrument years’ operating time were obtained. [Continues.]