TEMPERATURE AND PRESSURE SWITCHES - GUARDIANS OF LOOPS - NODES OF SAFETY

Seldom boasting an address on the plant databus, yet often guarding the high or low state of a critical process or factory variable, some switches rate high on the automation parts list. Inbuilt sensors give them a special breed of guardianship, tucked into a single package. Decisive control action, triggered by a potentially catastrophic variable, can quickly demonstrate impressive on-line utility. Temperature is one example of such a variable; so is pressure. This article discusses switches that respond to temperature or pressure setpoints in hazardous and normal monitoring situations.