A Guide to the Automation Body of Knowledge

Introduction

Good control requires measurements that are accurate, reliable,responsive and maintainable. These factors are influenced by thechoice of principle used for the measurement, the detailedspecifications and features of the instrument selected andspecified, how well the instrument and its installation ismaintained, and particularly the installation details.

The vast majority of physical measurements in processes are ofthe big four: flow, pressure, level, and temperature. This topicwill focus on the more popular methods for measuring thesevariables. Analytical measurements are covered in the next topic.While this topic is titled “process” instrumentation because thelarger number of applications are in process and utilityapplications, much of this instrumentation is used in many otherareas of automation application wherever continuous measurementsare needed.

Much of the focus in this topic is on compact”transmitters”—devices that combine the sensor and communicatingelectronics in one package. Some temperature measurements are anexception to this, since those devices often separate the sensorand the communicating electronics. These transmitters sometimestake on different names: level transmitters become level gauges andflow transmitters become flowmeters.

Edition:

2

Published:

01/01/2006

Number of Pages:

522