By Lou Heavner, Emerson

Chemical engineers are ideal candidates for control engineering jobs. They understand processes and process design. However, many have never considered or studied process dynamics. Process engineers often provide the preliminary instrumentation and control requirements for new projects. Control engineering is just the next step. Control engineers try to identify and understand sources of process variability that can impact product quality, and then reduce the variability to mitigate its adverse economic effects. Even if a process engineer never becomes a control engineer, being aware of process control requirements and challenges will lead to better process designs. This article provides information to aid chemical engineers in their understanding of how to reduce process variability by better controlling processes. »

Differential pressure (DP) measurements are used in many branches of the chemical process industries (CPI) for a variety of measuring tasks. Besides mechanical measurements via active pressure lines or chemical seals, electronic differential pressure measurements are now also available. But what is the optimum solution for the user? This article explains the operating mode for both, as well as the differences between the two systems. The main focus is on the measuring accuracy and selection criteria. A few practical examples are also presented. »