Metering Pumps

A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…

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Relay Circuits and Ladder Diagrams

Electromechanical relays may be connected together to perform logic and control functions, acting as logic…

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FOUNDATION Fieldbus H1 Protocol Physical Layer

Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…

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Sliding-stem Valves

A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…

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Temperature Switches

A temperature switch is one detecting the temperature of some substance. Temperature switches often use…

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Circuit Breakers and Disconnects

Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…

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Chromatography: Methods, Detectors and Species

Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…

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Functional Diagrams: the Flow of Information within a Control System

A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…

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Temperature Sensor Accessories

One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…

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Differential (87) Current Protection

One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…

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Rotary-stem Valves

A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…

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Laser Spectroscopy

A laser is a light source emitting waves of light that not only share the exact same frequency (color)…

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Change-of-quantity Flow Measurement

Flow, by definition, is the passage of material from one location to another over time. So far this chapter…

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Memory Maps and I/O Addressing

A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…

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Basic Operation of a Gas Chromatograph

This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…

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Ethernet networks: Repeaters, Cabling and Switching Hubs

An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…

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Instruction List (IL) Programming

(Will be addressed in future versions of this book)

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Control Valve Sizing

When control valves operate between fully open and fully shut, they serve much the same purpose in process…

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Comparison of Op-Amp Circuits With Analogous Pneumatic Mechanisms

Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…

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LRV and URV Settings, Digital Trim (Digital Transmitters)

The advent of “smart” field instruments containing microprocessors has been a great advance for…

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