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Pressure Sensor Accessories

Pressure Sensor Accessories

Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…


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Function Block Diagram (FBD) Programming

Function Block Diagram (FBD) Programming

(Will be addressed in future versions of this book)


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Ladder Diagram (LD) Structure Commands

Ladder Diagram (LD) Structure Commands

The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…


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Concepts and Laws of Probability

Concepts and Laws of Probability

While the term “probability” may evoke images of imprecision, probability is in fact an exact…


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Feedforward Control

Feedforward Control

“Feedforward” is a rather under-used control strategy capable of managing a great many types of…


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Boiler Water Level Control System Example

Boiler Water Level Control System Example

Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…


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Control Valve Actuators

Control Valve Actuators

The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…


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VSD and VFD Motor Drive Features

VSD and VFD Motor Drive Features

Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…


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Indicators, Recorders, Process Switches and Alarms

Indicators, Recorders, Process Switches and Alarms

So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…


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Common Diagnostic Mistakes in Control Systems

Common Diagnostic Mistakes in Control Systems

Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…


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Electrical Signal and Control Wiring

Electrical Signal and Control Wiring

There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…


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Ladder Diagram (LD) Programming Contacts and Coils

Ladder Diagram (LD) Programming Contacts and Coils

In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…


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Legal Code

Legal Code

Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…


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Design-based Fortifications

Design-based Fortifications

A design-based fortification is one rooted in technical details of system architecture and functionality. Some…


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Temperature Sensor Accessories

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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Valve Positioners

Valve Positioners

The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…


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LRV and URV Settings, Digital Trim (Digital Transmitters)

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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Differential (87) Current Protection

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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Safety Instrumented Functions and Systems

Safety Instrumented Functions and Systems

A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…


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Memory Maps and I/O Addressing

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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Pipe and Pipe Fittings

Pipe and Pipe Fittings

Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…


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Advantages and Disadvantages of Pneumatic Instruments

Advantages and Disadvantages of Pneumatic Instruments

The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…


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Rotating Magnetic Fields in Three-phase AC Induction Motors

Rotating Magnetic Fields in Three-phase AC Induction Motors

The following animation shows how the “rotating” magnetic field of a three-phase AC induction…


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What are Simple Machines?

What are Simple Machines?

A machine in the broad sense of the word is any device designed to translate some form of energy into useful…


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Fundamental Principles of Industrial Instrumentation

Fundamental Principles of Industrial Instrumentation

Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…


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Pneumatic Sensing Elements

Pneumatic Sensing Elements

Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…


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High-reliability Control Systems

High-reliability Control Systems

As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…


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Dispersive Spectroscopy

Dispersive Spectroscopy

The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…


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Analog Electronic PID Controllers

Analog Electronic PID Controllers

Although analog electronic process controllers are considered a newer technology than pneumatic process…


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An Analogy for Calibration Vs Ranging

An Analogy for Calibration Vs Ranging

The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…


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Policy-based Fortifications

Policy-based Fortifications

These fortifications focus on human behavior rather than system design or component selection. In some ways…


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Scientific System diagnosis and Scientific Reasoning

Scientific System diagnosis and Scientific Reasoning

At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…


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Positive Displacement Flowmeters

Positive Displacement Flowmeters

A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…


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Stoichiometry and the Law of Mass Conservation

Stoichiometry and the Law of Mass Conservation

Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…


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Pneumatic Actuator Response

Pneumatic Actuator Response

A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…


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Teaching Technical Practices (Labwork)

Teaching Technical Practices (Labwork)

Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…


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Flow Switches

Flow Switches

A flow switch is one that detects the flow of some fluid through a pipe. Flow switches often use…


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Mechanical Pressure Elements

Mechanical Pressure Elements

Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…


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General Problem-solving Techniques

General Problem-solving Techniques

A variety of problem-solving techniques have been presented for students over the years which are all helpful…


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Heuristic PID Tuning Procedures

Heuristic PID Tuning Procedures

In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…


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Electrical Sensors: Potential Transformers (PTs) and Current Transformers (CTs)

Electrical Sensors: Potential Transformers (PTs) and Current Transformers (CTs)

The two “process variables” we rely on most heavily in the field of electrical measurement and…


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Flow Measurement in Open Channels

Flow Measurement in Open Channels

Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…


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4-wire (“self-powered”) Transmitter Current Loops

4-wire (“self-powered”) Transmitter Current Loops

DC electric current signals may also be used to communicate process measurement information from transmitters…


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Introduction to Inductors and Inductance

Introduction to Inductors and Inductance

Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…


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Level Sensor Accessories

Level Sensor Accessories

Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…


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FOUNDATION Fieldbus Design Philosophy

FOUNDATION Fieldbus Design Philosophy

To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…


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True Mass Flowmeters

True Mass Flowmeters

Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…


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Self-balancing Pneumatic Instruments Principles

Self-balancing Pneumatic Instruments Principles

A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…


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Transfer Function Analysis

Transfer Function Analysis

An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…


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Understanding How Three-phase Electric Motors Work

Understanding How Three-phase Electric Motors Work

The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…


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Force-balance Pressure Transmitters

Force-balance Pressure Transmitters

An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…


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Design-based Fortifications

Design-based Fortifications

A design-based fortification is one rooted in technical details of system architecture and functionality. Some…


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Periodic Table of the Ions

Periodic Table of the Ions


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Policy-based Fortifications

Policy-based Fortifications

These fortifications focus on human behavior rather than system design or component selection. In some ways…


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Ethernet networks: Repeaters, Cabling and Switching Hubs

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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Rotary-stem Valves

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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Function Block Diagram (FBD) Programming

Function Block Diagram (FBD) Programming

(Will be addressed in future versions of this book)


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Electromagnetism Basics

Electromagnetism Basics

The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…


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Gas Filter Correlation (GFC) Spectroscopy

Gas Filter Correlation (GFC) Spectroscopy

Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…


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FOUNDATION Fieldbus H1 Protocol Physical Layer

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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