Measurement Instruments

In process plants, measurement instruments are used to gather process values in order to monitor and control the operation. The measured values are logged at the process control system and processed for different purposes, such as to control individual components and to start and stop the entire plant or subsystems thereof. The requirements for the reliability of the measurement depend on what it is used for and the possible consequences of faulty values. High requirements can necessitate several independent measurement instruments or the inclusion of specific safety features. Depending on the process value to be measured the accuracy of the measurement depends among other things on the mounting position of the measurement instrument, the location of the connection relative to the process volume, and, in case of process volumes containing flowing media, the condition of the sections up- and downstream of the measurement instrument.