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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FOUNDATION Fieldbus Design Philosophy

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

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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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Interconnected Generators

Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…

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What is Internet Protocol (IP)?

I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…

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ANSI/IEEE Function Number Codes

In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…

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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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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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Thermistors and Resistance Temperature Detectors (RTDs)

One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…

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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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Teaching Technical Theory

Learning is not merely a process of information transfer. It is first and foremost a transformation of…

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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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FOUNDATION Fieldbus H1 Protocol Data Link Layer

Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…

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Circuit Failure Analysis

Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…

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Input/Output (I/O) Capabilities of PLCs

Every programmable logic controller must have some means of receiving and interpreting signals from real-world…

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Fluorescence Measurement

When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…

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Controller Output Current Loops

The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…

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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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The s Variable: Euler’s Relation and Phasor Expressions of Waveforms

A powerful mathematical concept useful for analyzing practically any physical system – electrical…

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Measuring Electrical Conductivity

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

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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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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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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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P, I, and D Responses Graphed

Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…

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Process/Instrument Suitability

Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…

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Conservation Laws

The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…

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Wastewater Disinfection Example

The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…

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Digital Multimeter (DMM) Tips and Tricks

The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…

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Metric Prefixes and Prefix Scale

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Techniques for Analyzing Control Strategies

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

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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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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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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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Practical Topic Coverage

Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…

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Valve Packing

Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…

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FOUNDATION Fieldbus H1 Protocol Segment Troubleshooting

Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…

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Numerical Integration

As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…

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Use of Line Reactors

Regulating the electric power sent to an electric motor is a task performed by high-speed switching…

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Level Sensor Accessories

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

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Assessing Student Learning

As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…

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