The term “grid” refers to the conductors and equipment…
In a manually-controlled process, a human operator directly actuates…
Circuit breakers used in residential, commercial, and light industrial…
A completely different way of measuring liquid level in vessels is to…
The efficient identification and correction of instrument calibration…
Process analyzers measure the concentration of specific substances for…
Weight-based level instruments sense process level in a vessel by…
The vast majority of modern process transmitters (both analog and…
For better or worse, there are no fewer than three different forms of…
An important type of “accessory” relay, especially for…
An electromechanical relay is an electrical switch actuated by an…
A hand switch is exactly what the name implies: an electrical switch…
An on/off valve is the fluid equivalent of an electrical switch: a…
As discussed at the beginning of this chapter, instrumentation safety…
A limit switch detects the physical motion of an object by direct…
Capacitive level instruments measure electrical capacitance of a…
The fundamental principle of electromagnetism is that an electric…
The advent of “smart” field instruments containing…
A special type flowmeter suited for powdered or granular solids is the…
(Will be addressed in future versions of this book)
Using filter cells to eliminate wavelengths associated with…
To summarize some of the key points and concepts for teaching: Do not…
Earlier in this chapter you were shown a model of a nitrogen atom with…
The vast majority of PID controllers in service today are digital in…
One very convenient feature of waves is that their properties are…
Disturbances in the liquid tend to complicate liquid level…
Many years ago, when I was first learning about electricity, I…
A unique form of differential pressure-based flow measurement deserves…
A whole class of problem-solving techniques focuses on altering the…
This section shows some of the many instrument symbols found in…
In addition to Ohm’s Law, we have a set of rules describing how…
Level gauges are perhaps the simplest indicating instrument for liquid…
It is possible to convey electrical power and communicate analog…
A great many precision instruments use the principle of balance to…
A very helpful method for understanding the operation of proportional,…
Data-processing modules within FF systems are known as function…
RTDs are completely passive sensing elements, requiring the…
“Radio” systems use electromagnetic fields to communicate…
The following animation shows how a radio-energy pulse travels down…
Regardless of valve type, all stem-actuated control valves require…
