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Lessons in Instrumentation TOC

Lessons in Industrial Instrumentation


Introduction to calculus

The concept of differentiation

The concept of integration

How derivatives and integrals relate to one another



Terms and Definitions

Metric prefixes

Unit conversions and physical constants

Conversion formulae for temperature

Conversion factors for distance

Conversion factors for volume

Conversion factors for velocity

Conversion factors for mass

Conversion factors for force

Conversion factors for area

Conversion factors for pressure (either all gauge or all absolute)

Conversion factors for pressure (absolute pressure units only)

Conversion factors for energy or work

Conversion factors for power

Terrestrial constants

Properties of water

Miscellaneous physical constants

Weight densities of common materials

Dimensional analysis

The International System of Units

Conservation Laws

Classical mechanics

Newton’s Laws of Motion

Work, energy, and power

Mechanical springs

Rotational motion

Elementary thermodynamics

Heat versus Temperature



Heat transfer

Specific heat and enthalpy

Phase changes

Phase diagrams and critical points

Thermodynamic degrees of freedom

Applications of phase changes

Fluid mechanics


Pascal’s Principle and hydrostatic pressure

Fluid density expressions


Systems of pressure measurement


Gas Laws

Fluid viscosity

Reynolds number

Law of Continuity

Viscous flow

Bernoulli’s equation

Torricelli’s equation

Flow through a venturi tube



Terms and Definitions

Atomic theory and chemical symbols

Periodic table of the elements

Electronic structure


Emission spectroscopy

Absorption spectroscopy

Formulae for common chemical compounds

Molecular quantities


Balancing chemical equations by trial-and-error

Balancing chemical equations using algebra

Stoichiometric ratios

Energy in chemical reactions

Periodic table of the ions

Ions in liquid solutions



DC electricity

Electrical voltage

Electrical current

Electron versus conventional flow

Electrical resistance and Ohm’s Law

Series versus parallel circuits

Kirchhoff’s Laws

Electrical sources and loads


Bridge circuits

Component measurement

Sensor signal conditioning




AC electricity

RMS quantities

Resistance, Reactance, and Impedance

Series and parallel circuits

Phasor mathematics

Crank diagrams and phase shifts

Complex numbers and phase shifts

Phasor expressions of impedance

Euler’s Relation and crank diagrams

The s variable

Transmission lines


Introduction to Industrial Instrumentation

Example: boiler water level control system

Example: wastewater disinfection

Example: chemical reactor temperature control

Other types of instruments



Process switches and alarms



Instrumentation documents

Process Flow Diagrams

Process and Instrument Diagrams

Loop diagrams

SAMA diagrams

Instrument and process equipment symbols

Line types

Process/Instrument line connections

Instrument bubbles

Process valve types

Valve actuator types

Valve failure mode

Flow measurement devices (flowing left-to-right)

Process equipment

SAMA diagram symbols

Single-line electrical diagram symbols

Instrument identification tags


Instrument connections

Pipe and pipe fittings

Flanged pipe fittings

Tapered thread pipe fittings

Parallel thread pipe fittings

Sanitary pipe fittings

Tube and tube fittings

Compression tube fittings

Common tube fitting types and names

Bending instrument tubing

Electrical signal and control wiring

Connections and wire terminations

DIN rail

Signal coupling and cable separation

Electric field (capacitive) de-coupling

Magnetic field (inductive) de-coupling

High-frequency signal cables


Discrete process measurement

“Normal” status of a switch

Hand switches

Limit switches

Proximity switches

Pressure switches

Level switches

Temperature switches

Flow switches


Discrete control elements

On/off valves

Fluid power systems

Solenoid valve actuators

2-way solenoid valves

3-way solenoid valves

4-way solenoid valves

Normal energization states

On/off electric motor control circuits

AC induction motors

Starter (contactor) relays

Motor overload protective devices

Motor control circuit wiring


Relay control systems

Control relays

Relay circuits


Programmable Logic Controllers

PLC examples

Input/Output (I/O) capabilities

Discrete I/O

Analog I/O

Network I/O

Logic programming

Memory maps and I/O addressing

Ladder Diagram (LD)

Structured Text (ST)

Instruction List (IL)

Function Block Diagram (FBD)

Sequential Function Chart (SFC)

Human-Machine Interfaces

How to teach yourself PLC programming


Analog electronic instrumentation

4 to 20 mA analog current signals

Relating 4 to 20 mA signals to instrument variables

Example calculation: controller output to valve

Example calculation: flow transmitter

Example calculation: temperature transmitter

Example calculation: pH transmitter

Example calculation: reverse-acting I/P transducer signal

Graphical interpretation of signal ranges

Controller output current loops

4-wire (“self-powered”) transmitter current loops

2-wire (“loop-powered”) transmitter current loops

Troubleshooting current loops

Using a standard milliammeter to measure loop current

Using a clamp-on milliammeter to measure loop current

Using “test” diodes to measure loop current

Using shunt resistors to measure loop current

Troubleshooting current loops with voltage measurements

Using loop calibrators

NAMUR signal levels


Pneumatic instrumentation

Pneumatic sensing elements

Self-balancing pneumatic instrument principles

Pilot valves and pneumatic amplifying relays

Analogy to opamp circuits

Analysis of practical pneumatic instruments

Foxboro model 13A differential pressure transmitter

Foxboro model E69 “I/P” electro-pneumatic transducer

Fisher model 546 “I/P” electro-pneumatic transducer

Fisher-Rosemount model 846 “I/P” electro-pneumatic transducer

Proper care and feeding of pneumatic instruments

Advantages and disadvantages of pneumatic instruments


Digital data acquisition and networks

Digitization of analog quantities


Sampling rate

Digital data communication theory

Serial communication principles

Physical encoding of bits

Communication speed

Data frames

Channel arbitration

Code sets

The OSI Reference Model

EIA/TIA-232, 422, and 485 networks


EIA/TIA-422 and EIA/TIA-485

Ethernet networks

Repeaters (hubs)

Ethernet cabling

Switching hubs

Internet Protocol (IP)

IP addresses

Subnetworks and subnet masks

IP version


Command-line diagnostic utilities

Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)

The HART digital/analog hybrid standard

HART multidrop mode

HART multi-variable transmitters


Modbus data frames

Modbus function codes and addresses

Modbus function command formats


FOUNDATION Fieldbus instrumentation

FF design philosophy

H1 FF Physical layer

Segment topology

Coupling devices

Electrical parameters

Cable types

Segment design

H1 FF Data Link Layer

Device addressing

Communication management

Device capability

FF function blocks

Analog function blocks versus digital function blocks

Function block location

Standard function blocks

Device-specific function blocks

Status propagation

Function block modes

H1 FF device configuration and commissioning

Configuration files

Device commissioning

Calibration and ranging

H1 FF segment troubleshooting

Cable resistance

Signal strength

Electrical noise

Using an oscilloscope on H1 segments

Message re-transmissions


Instrument calibration

Calibration versus re-ranging

Zero and span adjustments (analog transmitters)

Damping adjustments

LRV and URV settings, digital trim (digital transmitters)

Calibration procedures

Linear instruments

Nonlinear instruments

Discrete instruments

Typical calibration errors

As-found and as-left documentation

Up-tests and Down-tests

NIST traceability

Instrument turndown

Practical calibration standards

Electrical standards

Temperature standards

Pressure standards

Flow standards

Analytical standards


Continuous pressure measurement


Mechanical pressure elements

Electrical pressure elements

Piezoresistive (strain gauge) sensors

Differential capacitance sensors

Resonant element sensors

Mechanical adaptations

Force-balance pressure transmitters

Differential pressure transmitters

Pressure measurement applications

Inferential measurement applications

Pressure sensor accessories

Valve manifolds

Bleed (vent) fittings

Pressure pulsation damping

Remote and chemical seals

Filled impulse lines

Purged impulse lines

Heat-traced impulse lines

Water traps and pigtail siphons

Mounting brackets

Heated enclosures

Process/instrument suitability


Continuous level measurement

Level gauges (sightglasses)


Hydrostatic pressure

Bubbler systems

Transmitter suppression and elevation

Compensated leg systems

Tank expert systems

Hydrostatic interface level measurement


Torque tubes

Displacement interface level measurement


Ultrasonic level measurement

Radar level measurement

Laser level measurement

Magnetostrictive level measurement




Level sensor accessories


Continuous temperature measurement

Bi-metal temperature sensors

Filled-bulb temperature sensors

Thermistors and Resistance Temperature Detectors (RTDs)

Temperature coefficient of resistance (α)

Two-wire RTD circuits

Four-wire RTD circuits

Three-wire RTD circuits

Self-heating error


Dissimilar metal junctions

Thermocouple types

Connector and tip styles

Manually interpreting thermocouple voltages

Reference junction compensation

Law of Intermediate Metals

Software compensation

Extension wire

Side-effects of reference junction compensation

Burnout detection

Non-contact temperature sensors

Temperature sensor accessories

Process/instrument suitability


Continuous fluid flow measurement

Pressure-based flowmeters

Venturi tubes and basic principles

Volumetric flow calculations

Mass flow calculations

Square-root characterization

Orifice plates

Other differential producers

Proper installation

High-accuracy flow measurement

Equation summary

Laminar flowmeters

Variable-area flowmeters


Weirs and flumes

Velocity-based flowmeters

Turbine flowmeters

Vortex flowmeters

Magnetic flowmeters

Ultrasonic flowmeters

Positive displacement flowmeters

Standardized volumetric flow

True mass flowmeters

Coriolis flowmeters

Thermal flowmeters


Change-of-quantity flow measurement

Insertion flowmeters

Process/instrument suitability


Continuous analytical measurement

Conductivity measurement

Dissociation and ionization in aqueous solutions

Two-electrode conductivity probes

Four-electrode conductivity probes

Electrodeless conductivity probes

pH measurement

Colorimetric pH measurement

Potentiometric pH measurement


Optical analyses

Dispersive spectroscopy

Non-dispersive spectroscopy



Safety gas analyzers

Oxygen gas

Lower explosive limit (LEL)

Hydrogen sulfide gas

Carbon monoxide gas

Chlorine gas


Machine vibration measurement

Vibration physics

Sinusoidal vibrations

Non-sinusoidal vibrations

Vibration sensors

Monitoring hardware

Mechanical vibration switches


Signal characterization

Flow measurement in open channels

Liquid volume measurement

Radiative temperature measurement

Analytical measurements


Final control elements

Control valves

Sliding-stem valves

Rotary-stem valves

Dampers and louvres

Valve packing

Valve seat leakage

Control valve actuators

Valve failure mode

Actuator bench-set

Pneumatic actuator response

Valve positioners


Control valve sizing

Control valve characterization

Control valve problems

Variable-speed motor controls

DC motor speed control

AC motor speed control

Motor drive features

Metering pumps


Principles of feedback control

Basic feedback control principles

On/off control

Proportional-only control

Proportional-only offset

Integral (reset) control

Derivative (rate) control

Summary of PID control terms

Proportional control mode (P)

Integral control mode (I)

Derivative control mode (D)

P, I, and D responses graphed

Responses to a single step-change

Responses to a momentary step-and-return

Responses to two momentary steps-and-returns

Responses to a ramp-and-hold

Responses to an up-and-down ramp

Responses to a sine wavelet

Note to students regarding quantitative graphing

Different PID equations

Pneumatic PID controllers

Automatic and manual modes

Derivative and integral actions

Fisher MultiTrol

Foxboro model 43AP

Foxboro model 30

External reset (integral) feedback

Analog electronic PID controllers

Circuit design

Single-loop analog controllers

Multi-loop analog control systems

Digital PID controllers

Stand-alone digital controllers

Direct digital control (DDC)

SCADA and telemetry systems

Distributed Control Systems (DCS)

Fieldbus control

Practical PID controller features

Manual and automatic modes

Output and setpoint tracking

Alarm capabilities

Output and setpoint limiting


Note to students

Proportional-only control action

Integral-only control action

Proportional plus integral control action

Proportional plus derivative control action

Full PID control action


Process dynamics and PID controller tuning

Process characterization

Self-regulating processes

Integrating processes

Runaway processes

Steady-state process gain

Lag time

Multiple lags (orders)

Dead time


Before you tune

Identifying operational needs

Identifying process and system hazards

Identifying the problem(s)

Final precautions

Quantitative PID tuning procedure

Ziegler-Nichols closed-loop (“Ultimate Gain”)

Ziegler-Nichols open-loop

Heuristic PID tuning procedures

Features of P, I, and D actions

Tuning recommendations based on process dynamics

Tuning techniques compared

Tuning a “generic” process

Tuning a liquid level process

Tuning a temperature process

Note to students

Basic process control strategies

Supervisory control

Cascade control

Ratio control

Relation control

Feedforward control

Feedforward with dynamic compensation

Dead time compensation

Lag time compensation

Lead/Lag and dead time function blocks

Limit, Selector, and Override controls

Limit controls

Selector controls

Override controls


Process safety and instrumentation

Classified areas and electrical safety measures

Classified area taxonomy

Explosive limits

Protective measures

Concepts of probability and reliability

Mathematical probability

Laws of probability

Practical measures of reliability

High-reliability systems

Design and selection for reliability

Preventive maintenance

Component de-rating

Redundant components

Proof tests and self-diagnostics

Safety Instrumented Functions and Systems

SIS sensors

SIS controllers (logic solvers)

SIS final control elements

Safety Integrity Levels

SIS example: burner management systems

SIS example: water treatment oxygen purge system

SIS example: nuclear reactor scram controls


Instrument system problem-solving

Classic mistakes to avoid

Helpful “tricks” using a digital multimeter (DMM)

Recording unattended measurements

Avoiding “phantom” voltage readings

Non-contact AC voltage detection

Detecting AC power harmonics

Identifying noise in DC signal paths

Generating test voltages

Using the meter as a temporary jumper

 Doctor Strangeflow, or how I learned to relax and love Reynolds numbers

***All articles linked from here are works of Tony R. Kuphaldt from Lessons in Instrumentation

Lessons In Instrumenation copyright (C) 2000-2012 Tony R. Kuphaldt, under the terms and conditions of the Design Science License.

Comments (10)Add Comment
written by Neil, July 17, 2012
Dude, you might wanna give some credit to Mr. Tony R. Kuphaldt and the Open Book Project.
Richard Babb
Thank you!
written by Richard Babb, August 12, 2012
I just want to thank everyone involved in the making and support of this website. This has been such an asset to my coworkers and myself thank you from New Orleans, Louisiana!!!!! Have a happy instrumentation day!
written by Michael , September 19, 2012
dude neil, the credit is on the front page..
written by Aaron, October 28, 2015
hi, thanks for the great site. easy to navigate and lots of useful information. i was wondering if and when the last few sections would be filled - PID principles and the process dynamics and process safety topics that are missing.

thanks again
!! Thanks !!
written by Aarekh Mehrotra, May 16, 2016
Dear Mr. Tony R. Kuphaldt,
Thanks a ton Tony for sharing your work in Instrumentation.
Information provided in very nicely categorised and explained.
written by Plant Maintenance Engineer, October 28, 2016
one stop shop for very relevant information for a plant maintenance engineer. Highly appreciated
Maintenance Manager
written by Ahmed Ragab, August 21, 2017
Thanks A lot
Maintenance Manager
written by Ahmed Ragab, August 21, 2017
Thanks, A lot
written by Rima , August 31, 2017
Many Thanks to Mr. Tony for sharing such lesson in Instrumentation.

I&C Instructor
written by G. Rublein, March 22, 2018
Everytime I click on a topic, I briefly get the page but suddenly I get redirected to another website. Something is wrong.

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