An optimal alarm-system design method, which takes full advantage of the inherent hardware and spatial redundancies in a mass-flow network, is proposed. In particular, systematic procedures are developed to identify independent measurement methods for the flow rate of any stream in the process and to synthesize corresponding alarm generation logic. To implement the suggested alarm strategy, the formulas for evaluating conditional probabilities of type I and II mistakes are also derived. The results of applying the proposed alarm system to the application example show that the approach taken in this work is effective in suppressing the latter mistakes. Further, this system is superior to any of the existing alarm techniques in the sense that it can be appropriately tailored to minimize the expected loss due to misjudgments in generating alarms.