If You Can’t See It You Can’t Detect It

Fundamental to all process monitoring and control is observability, the quality that the state of a system (e.g., a pipeline leaking or not leaking) is actually discernable from the measurements available. Here are four examples of how measurement issues obliterated productive monitoring. In one example a transient phase change in a process loop results in gross mis-measurement at one end. A second example illustrates that buying a flow meter does not always result in flow measurement. A third example shows a pipeline in which the readings at one end show absolutely no relationship to the other. The fourth example shows a pipeline that appears to be leaking at one end but fine at the other. The concept of observability provides some structure for thinking through these situations and developing solutions.