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Level Switches

Level Switches

A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…


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Transmitter Damping Adjustments

Transmitter Damping Adjustments

The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…


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Applications of Spectroscopy for Analytical Measurement

Applications of Spectroscopy for Analytical Measurement

Much of our knowledge about atomic structure comes from experimental data relating the interaction between…


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Digital Data Communication Theory

Digital Data Communication Theory

One of the great benefits of digital technology is the ability to communicate vast amounts of information over…


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Differential Pressure Transmitters

Differential Pressure Transmitters

One of the most common, and most useful, pressure measuring instruments in industry is the differential…


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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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Electrical Sources and Electronic Load

Electrical Sources and Electronic Load

By definition, a source is a device delivering energy into a system, while a load is a device extracting…


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Non-dispersive Luft Detector Spectroscopy

Non-dispersive Luft Detector Spectroscopy

Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…


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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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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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Distance (21) Protection

Distance (21) Protection

A form of protection against faults on long-distance power lines is called distance relaying, so named because…


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Null-balance Voltage Measurement

Null-balance Voltage Measurement

A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…


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Comparison of  Op-Amp Circuits With Analogous Pneumatic Mechanisms

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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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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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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Electrical Pressure Elements

Electrical Pressure Elements

Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…


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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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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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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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Cascade Control

Cascade Control

A simple control system drawn in block diagram form looks like this: Information from the measuring device…


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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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Measuring Electrical Conductivity

Measuring Electrical Conductivity

The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…


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Ultrasonic (Sound) Echo Level Measurement

Ultrasonic (Sound) Echo Level Measurement

A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…


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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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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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Digital Representation of Text

Digital Representation of Text

Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…


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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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The Concept of Integration

The Concept of Integration

Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…


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Pneumatic PID Controllers

Pneumatic PID Controllers

A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…


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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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Techniques for Analyzing Control Strategies

Techniques for Analyzing Control Strategies

Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…


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Introduction to Power System Automation

Introduction to Power System Automation

Those familiar with industrial instrumentation will find much within the electric power industry remarkably…


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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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On/off Electric Motor Control Circuits

On/off Electric Motor Control Circuits

An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…


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FOUNDATION Fieldbus H1 Protocol Device Configuration and Commissioning

FOUNDATION Fieldbus H1 Protocol Device Configuration and Commissioning

Fieldbus devices require far more attention in their initial setup and commissioning than their analog…


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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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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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Ions in Liquid Solutions

Ions in Liquid Solutions

Many liquid substances undergo a process whereby their constituent molecules split into positively and…


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WirelessHART Radio Communication Standard

WirelessHART Radio Communication Standard

An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…


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Difference Between Calibration and Re-ranging

Difference Between Calibration and Re-ranging

What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…


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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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Glossary of Cyber-security Terms

Glossary of Cyber-security Terms

Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…


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Different PID Equations

Different PID Equations

For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…


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Radio-energy Pulse in Guided-wave Radar Level Measurement

Radio-energy Pulse in Guided-wave Radar Level Measurement

The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…


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Tuning PID Controllers

Tuning PID Controllers

Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…


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The Difference Between Series and Parallel Circuits

The Difference Between Series and Parallel Circuits

In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…


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On/off Shut-off Valves

On/off Shut-off Valves

An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…


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Material Volume Measurement

Material Volume Measurement

A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…


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Tube and Tube Fittings

Tube and Tube Fittings

Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…


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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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Digital Representation of Numerical Data

Digital Representation of Numerical Data

Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…


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Basics of Electrical Current

Basics of Electrical Current

Current is the name we give to the motion of electric charges from a point of high potential to a point of low…


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Insertion Flowmeters

Insertion Flowmeters

This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…


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Introduction to Capacitors and Capacitance

Introduction to Capacitors and Capacitance

Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…


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Diagnosing Feedback Control Problems

Diagnosing Feedback Control Problems

Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…


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Sequential Function Chart (SFC) Programming

Sequential Function Chart (SFC) Programming

(Will be addressed in future versions of this book)


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Non-contact Temperature Sensors

Non-contact Temperature Sensors

Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…


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Instrument Identification Tags

Instrument Identification Tags

Up until this point, we have explored various types of instrumentation diagram, each one making reference to…


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What is Electrical Power?

What is Electrical Power?

Since we often use electricity to convey energy from one location to another, it is important to be able to…


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Digital Data Communication Theory

Digital Data Communication Theory

One of the great benefits of digital technology is the ability to communicate vast amounts of information over…


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