inst241_sec1

INST 241 (Temperature and Flow Measurement), section 1

Lab

Temperature measurement loop: Questions 91 and 92, completed objectives due by the end of day 4,section 2Bulleted questions following lab objectives to be reviewed orally during lab time on day 4, section 2

Feedback questions

Questions 81 through 90, due at the end of day 4

Exam

Day 5 of next section – only a simple calculator may be used!Question 93 previews the mastery exam circuit-building activity

Recommended daily schedule

Day 1

Theory session topic: Temperature measurement technologies

Questions 1 through 20; answer questions 1-11 in preparation for discussion (remainder for practice)

Day 2

Theory session topic: Principles of heat and temperature


Day 3

Theory session topic: RTDs and thermistors


Day 4

Theory session topic: Thermocouples


Feedback questions (81 through 90) due at the end of the day

1

INST 241 (Temperature and Flow Measurement)

Credits/hours: 6 credits = 108 clock hours

Prerequisite or corequisite: INST 240 (Pressure and Level Measurement)

Course description: In this course you will learn how to precisely measure both temperature and fluidflow in a variety of applications, as well as accurately calibrate and efficiently troubleshoot temperature andflow measurement systems.

Program outcomes addressed:

(1) Communication; Communicates and expresses thoughts across a variety of mediums (verbal, written,visually) to effectively persuade, inform, and clarify ideas with colleagues.

(2) Time management; Arrives on time and prepared to work; budgets time and meets deadlines whenperforming technical tasks and projects.

(3) Safety; Complies with national, state, and local safety regulations when repairing, calibrating, andinstalling instruments.

(4) Diagnose and repair existing instruments; Assesses, diagnoses, and repairs faulty instruments inmeasurement and control systems using logical procedures and appropriate test equipment.

(5) Install and configure new instruments; Builds, configures and installs new instrument systemsaccording to plans, applying industry construction standards, and ensuring correct system operationwhen complete.

(7) Calibrate instruments; Assesses instrument accuracy and corrects inaccuracies using appropriatecalibration procedures and test equipment.

(8) Document instrument systems; Interprets and creates technical documents (electronic schematics,loop diagrams, and P&IDs) according to industry (EIA, ISA) standards.

(9) Self-directed learning; Selects and researches relevant information sources to learn newinstrumentation principles, technologies, and techniques.

Instructor contact information:

Tony Kuphaldt

Desmond P. McArdle Center

Bellingham Technical College

3028 Lindbergh Avenue

Bellingham, WA 98225-1599

(360)-752-8477 [office phone]

(360)-752-7277 [fax]

[email protected]

Required materials:

• Socratic worksheets: INST241 sec1.pdf, INST241 sec2.pdf, INST241 sec3.pdf, INST241 sec4.pdf

→ Download at: http://openbookproject.net/books/socratic/sinst

• Lessons in Industrial Instrumentation, By Tony R. Kuphaldt. Useful for all quarters of instruction.

→ Download at: http://openbookproject.net/books/socratic/sinst/book/liii.pdf

• Spiral-bound notebook for reading annotation, homework documentation, and note-taking. A separatenotebook for each course is recommended.

• Instrumentation reference CD-ROM (free, from instructor). This disk contains many tutorials anddatasheets in PDF format to supplement your textbook(s).

• Tool kit (see detailed list)

• Simple scientific calculator (non-programmable, non-graphing, no unit conversions, no numerationsystem conversions), TI-30Xa or TI-30XIIS recommended

2

Supplemental materials: (recommended, not required)• “BTCInstrumentation” channel on YouTube (http://www.youtube.com/BTCInstrumentation), hosts

a variety of short video tutorials and demonstrations on instrumentation.• Instrumentation, by Franklyn W. Kirk, published by American Technical Publishers. ISBN-10:

0826934234 ; ISBN-13: 978-0826934239. This text is light on detail and math, but does a good jobintroducing all the major principles and technologies in simple language. Excellent photographs andillustrations, too. Useful for all three quarters of instruction.

• Instrument Engineer’s Handbook, Volume 1: Process Measurement and Analysis, edited by Bela Liptak,published by CRC Press. 4th edition ISBN-10: 0849310830 ; ISBN-13: 978-0849310836.

• Purdy’s Instrument Handbook, by Ralph Dewey. ISBN-10: 1-880215-26-8. A pocket-sized field referenceon basic measurement and control.

• Cad Standard (CadStd) or similar AutoCAD-like drafting software (useful for sketching loop andwiring diagrams). Cad Standard is a simplified clone of AutoCAD, and is freely available at:http://www.cadstd.com

• Any good introductory physics textbook (Applied Physics by Tippens, or Conceptual Physics by Hewitt)• CRC Handbook of Chemistry and Physics

Student performance objectives:Assessment legend: [P] = Preparation, [L] = Lab, [F] = Feedback questions, [X] = Exam

• Mastery (must eventually be demonstrated without error)• [L] Calibration of thermocouple temperature transmitter to specified range and accuracy• [L] Calibration of RTD temperature transmitter to specified range and accuracy• [L] Calibration of liquid or gas flow transmitter to specified range and accuracy• [L] Create accurate as-built loop diagrams• [L] Create accurate P&IDs• [L] Troubleshoot a problem within an electronic (4-20 mA loop) temperature measurement system, given

a specified time to logically identify the location and nature of the problem• [L] Work safely and constructively within a team• [X1] Build a circuit to sense temperature using a thermocouple or RTD temperature transmitter• [X1] Convert between different units of temperature – only a simple calculator may be used!• [X1] Identify thermocouple types, color codes, metals, and temperature ranges• [X1] Calculate temperature or resistance of an RTD given the other variable• [X1] Calculate instrument calibration points given ranges• [X1] INST251 Review: identify proper controller action (direct or reverse) for a process• [X1] INST261 Review: sketch an equivalent ladder logic diagram for a given truth table• [X2] Build a circuit with a “smart” transmitter and use a HART communicator to re-range it• [X2] Identify operating principle for different types of flow-sensing elements• [X2] Identify characterization (linear vs. nonlinear) of different flow-sensing elements• [X2] Calculate new ∆P ranges for altered orifice flow ranges• [X2] Identify suitability of basic flow-measuring instruments to different processes• [X2] Identify proper installation configurations for different process fluids and flow instruments• [X2] Calculate turbine flowmeter calibration points given ranges (k factor)• [X2] INST251 Review: calculate or graph response of proportional-only controller to input changes over

time• [X2] INST262 Review: identify the purpose of a distributive control system (DCS)

• Proportional (graded on a percentage scale according to quality/quantity of fulfillment)• [P] Identify and use appropriate sources of information for independent learning• [L] Explain how to diagnose a hypothetical problem in a temperature measurement system• [L] Explain how to diagnose a hypothetical problem in a flow measurement system• [L] Explain or demonstrate a principle relevant to a temperature measurement system• [L] Explain or demonstrate a principle relevant to a flow measurement system• [L] Perform a basic math calculation relevant to a temperature measurmement system

3

• [L] Perform a basic math calculation relevant to a flow measurmement system• [L] Explain or demonstrate safety procedure or tool usage• [F] Qualitatively analyze a heat exchanger system• [F] Convert between different units of temperature• [F] Explain how a filled-bulb primary sensing element works• [F] Interpret the millivoltage output of a thermocouple• [F] Calorimetry calculation• [F] Solving for variables in an equation (kinetic energy equation)• [F] Calculating V, I, P in a series-parallel DC network (schematic)• [F] Calculate V and I in an AC transformer circuit (schematic)• [F] Qualitative fault analysis in a DC circuit (pictorial)• [F] Troubleshooting: OptoTRIAC solenoid control circuit• [F] Troubleshoot thermocouple problems• [F] Analyze an RTD bridge circuit• [F] Analyze a thermistor circuit• [F] Apply the physics of phase changes to a heat exchanger system• [F] Explain how Stefan-Boltzmann Law of radiated energy relates to practical temp measurement• [F] Trigonometric calculation (Law of Sines)• [F] Qualitative analysis of a practical equation (electrical resonant frequency)• [F] Calculating V in a DC network using KVL (schematic)• [F] Qualitative fault analysis in a DC circuit (pictorial)• [F] Troubleshooting: Automotive fuel gauge circuit (using current mirror)• [F] Describe and explain exchange of energy as fluid moves through an orifice• [F] Describe procedure for working with an insertion-type flow meter• [F] Compare and contrast weirs/flumes with orifice plates• [F] Determine a calibration table for all instruments in a flow-measurement loop• [F] Analyze pressure losses along pipes for linearity with flow rate• [F] Binary-to-hexadecimal conversion• [F] Oscilloscope waveform interpretation• [F] Calculate required time in an RC charge/discharge circuit (schematic)• [F] Loop wiring: two transmitters, two 4-20 mA input channels on MicroLogix PLC (pictorial)• [F] Troubleshooting: Digital logic gate security alarm circuit• [F] Calculate new ∆P range for an altered orifice flow range• [F] Explain vortex flow meter operation• [F] Explain magnetic flow meter operation• [F] Identify need for mass flow measurement• [F] Identify which types of flow-sensing elements require characterization (linear vs. nonlinear)• [F] Solving for variables in an equation (valve flow equation)• [F] Qualitative analysis of a practical equation (proportional controller equation)• [F] Qualitative fault analysis in a DC circuit (schematic)• [F] Three-phase motor connections (pictorial)• [F] Troubleshooting: Three-phase motor control circuit• [X1] Calculate electronic circuit parameters related to temperature measurement, both thermocouple

and RTD• [X1] Select an appropriate temperature-measuring technology for a specific application• [X1] Use the Ideal Gas Law to calculate pressure, volume, molecular gas quantity, or temperature given

the other variables.• [X1] Complete a simple circuit design for temperature measurement• [X2] Complex flow rate calculation(s)• [X2] Calculation(s) involving square root extraction• [X2] Flow stream conditioning requirements and techniques• [X2] Volumetric versus mass flow measurement• [X2] Flow measurement problem diagnosis

4

file INST241syllabus

5

Sequence of second-year Instrumentation courses

(or equivalent)

INST 200 -- 1 wk INST 205 -- 1 wk

GRADUATION !

Job Prep IIntro. to InstrumentationINST 206 -- 1 wk

Job Prep II

1st quarter 2nd quarter 3rd quarter

Pressure and LevelMeasurement

Measurement

MeasurementAnalytical

Temperature and Flow

INST 240 -- 4 wks

INST 241 -- 4 wks

Fal

l qu

arte

r

INST 242 -- 3 wks

Final ControlElements

Process Optimizationand Control Strategies

PID Controllersand Tuning

INST 250 -- 4 wks

INST 251 -- 4 wks

Win

ter

qu

arte

r

INST 252 -- 3 wks

Data AcquisitionSystems

Programmable LogicControllers

DCS and Fieldbus

INST 261 -- 4 wks

INST 262 -- 4 wks

Sp

rin

g q

uar

ter

INST 260 -- 3 wks

continuing students

(after completing all three quarters)

Core Electronics -- 1 year

file sequence

6

General student expectations

(Punctuality) You are expected to arrive at school on time (by 8:00 AM) every day. One late arrivalis permitted during the timespan of each sequential course (e.g. INST240, INST241, etc.) with no gradededuction. The grade deduction rate for late arrivals is 1% per incident.

(Attendance) You are expected to attend all day, every day. Each student has 12 “sick hours” per quarterapplicable to absences not verifiably employment-related, school-related, or weather-related. The gradededuction rate is 1% per hour of absence in any course. Each student must confer with the instructor toapply “sick hours” to any missed time – this is not done automatically for the student. Students may donateunused “sick hours” to whomever they specifically choose. You should contact your instructor and teammembers immediately if you know you will be late or absent. Absence on an exam day will result in a failinggrade for that exam, unless due to a documented emergency. Exams may be taken in advance for full credit.

(Participation) You are expected to participate fully in all aspects of the learning process includingindependent study, lab project completion, and classroom activities. It is solely your responsibility to catchup on all information missed due to absence. Furthermore, you shall not interfere with the participation ofothers in the learning process.

(Teamwork) You will work in instructor-assigned teams to complete lab assignments. Team membershipis determined by accumulated attendance and punctuality scores: students with similar participatory trendsare teamed together. Any student compromising team performance through frequent absence, habitualtardiness, or other disruptive behavior(s) will be expelled from their team and required to complete alllabwork independently for the remainder of the quarter.

(Preparation for theory sessions) You must dedicate at least 2 hours each day for reading assignmentsand homework questions to prepare yourself for theory sessions, where you will actively contribute your newknowledge. Graded quizzes and/or work inspections during each theory session will gauge your independentlearning. If absent, you may receive credit by having your preparatory work thoroughly reviewed prior tothe absence, or passing a comparable quiz after the absence.

(Feedback questions) You must complete and submit feedback questions for each section by the specifieddeadline. These are graded for accuracy and recorded as a “feedback” score. Plagiarism (presenting anyoneelse’s work as you own) in your answers will result in a zero score. It is okay to help one another learn thematerial, and to learn from outside sources, but your explanations must be phrased in your own words andwith your own work shown.

(Disciplinary action and instructor authority) The Student Code of Conduct (WashingtonAdministrative Codes WAC 495B-120) explicitly authorizes disciplinary action against the following typesof misconduct: academic dishonesty (e.g. cheating, plagiarism), dangerous or lewd behavior, harassment,intoxication, destruction of property, and/or disruption of the learning environment. Furthermore, the Codestates “Instructors have the authority to take whatever summary actions may be necessary to maintain orderand proper conduct in the classroom and to maintain the effective cooperation of the class in fulfilling theobjectives of the course.” Distractive or disruptive behavior such as (but not limited to) unauthorizedtelephone or computer use, disrespectful comments, sleeping, and conversation that either impede yourparticipation or the participation of others may result in temporary dismissal from class with attendancehours deducted.

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General grading and evaluation standards

Assessment criteria

• Mastery (all must be mastered – constitutes first 50% of course grade)• Mastery section of each lab exercise (unlimited attempts)• Mastery section of each exam including the hands-on circuit building or troubleshooting activity (up to

two attempts per sitting; up to three sittings); or mastery capstone assessment (unlimited attempts)

• Proportional (grades based on quality of fulfillment, counts toward last 50% of course grade)• Labwork, consisting of questions answered in an oral and demonstrative format (10% of grade)• Proportional section of all exams (20% of grade)• Feedback questions for all sections (20% of grade)• Daily quizzes demonstrating preparation for theory sessions (-1% per failed quiz)• Daily punctuality (-1% per incident of tardiness)• Attendance (-1% per hour past allotted “sick time”)• Destroyed items (-10% per incident) or purchase and replacement of the damaged item – This regards

avoidable incidents due to personal carelessness. When in doubt, ask the instructor how to properlyuse a tool or piece of equipment!

• Repaired instruments (+5% per item) – Instrument identified in need of repair by the instructor

Negative weighting represent objectives where 100% passing is a basic expectation (passing every quiz,punctuality every day, no accidents, etc.). Perfectly meeting these expectations does not count toward yourgrade, but failing to meet these basic expectations will result in grade loss.

Grading scaleAll grades are criterion-referenced (i.e. no grading on a “curve”)

• 100% ≥ A ≥ 95% 95% > A- ≥ 90%• 90% > B+ ≥ 86% 86% > B ≥ 83% 83% > B- ≥ 80%• 80% > C+ ≥ 76% 76% > C ≥ 73% 73% > C- ≥ 70% (minimum passing course grade)• 70% > D+ ≥ 66% 66% > D ≥ 63% 63% > D- ≥ 60% 60% > F

The proportional section of an exam may be taken only after taking the mastery section. Failing themastery exam will result in a 50% deduction from the proportional exam score, and you get a maximum oftwo re-takes to pass the mastery which must occur within three school days of the first attempt. Failure topass the mastery within three sittings will result in a failing grade for the course. Absence on a scheduledexam day will result in a 0% score for the proportional exam unless you provide documented evidence of anunavoidable emergency. You may receive half-credit on missed proportional exam questions after grading byexplaining your original mistake(s) and providing completely corrected responses on the first attempt.

If any other “mastery” objectives are not completed by their specified deadlines, your overall gradefor the course will be capped at 70% (C- grade), and you will have one more course day to complete theunfinished objectives. Failure to complete those mastery objectives by the end of that extra day (except inthe case of documented, unavoidable emergencies) will result in a failing grade (F) for the course.

Answers to “feedback questions” are due at the end of each course section. Full credit is given foreach question correctly and thoroughly answered, half credit for each question either not fully answeredor containing minor errors, and zero credit for major conceptual errors. Late submissions will receive zerocredit, unless due to a documented emergency.

“Lab questions” are assessed in a group format where students take turns answering questions from thelist at the instructor’s prompting. Grading follows the same rubric as for feedback questions: full creditfor thorough, correct answers; half credit for partially correct answers, and zero credit for major conceptualerrors. If you are absent during this assessment, you must submit written answers to all of the lab questions,which will be graded by the instructor.

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General tool and supply list

Wrenches• Combination (box- and open-end) wrench set, 1/4” to 3/4” – the most important wrench sizes are 7/16”,

1/2”, 9/16”, and 5/8”; get these immediately!• Miniature combination wrench set, 3/32” to 1/4”• Adjustable wrench, 6” handle• Hex wrench (“Allen” wrench) set, fractional – 1/16” to 3/8”

Note: when turning a bolt, nut, or tube fitting with a hexagonal body, the preferred ranking of handtools to use (from first to last) is box-end wrench or socket, open-end wrench, and finally adjustable wrench.Pliers should never be used to turn the head of a fitting or fastener unless it is absolutely unavoidable!

Pliers• Needle-nose pliers• Slip-joint pliers• Diagonal wire cutters

Screwdrivers• Slotted, 1/8” and 1/4” shaft• Phillips, #1 and #2• Jeweler’s screwdriver set

Measurement tools• Tape measure. 12 feet minimum• Vernier calipers, plastic okay

Electrical• Multimeter, Fluke model 87-IV or better• Wire strippers/terminal crimpers with a range including 10 AWG to 18 AWG wire• Soldering iron, 10 to 25 watt• Rosin-core solder• Package of compression-style fork terminals (e.g. Thomas & Betts “Sta-Kon” part number 14RB-10F,

14 to 18 AWG wire size, #10 stud size)

Safety• Safety glasses or goggles (available at BTC bookstore)• Earplugs (available at BTC bookstore)

Miscellaneous• Teflon pipe tape• Utility knife

You are recommended to engrave your name or place some other form of identifying mark on your tools,as you will be doing a lot of your work in teams, and it is easy to get tools mixed up. Also, lost tools getreturned to their owners much faster when they are marked!

An inexpensive source of high-quality tools is your local pawn shop. Look for name-brand tools withunlimited lifetime guarantees (e.g. Sears “Craftsman” brand, Snap-On, etc.).

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Methods of instruction

This course develops self-instructional and diagnostic skills by placing students in situations where theyare required to research and think independently. In all portions of the curriculum, the goal is to avoid apassive learning environment, favoring instead active engagement of the learner through reading, reflection,problem-solving, and experimental activities. The curriculum may be roughly divided into two portions:theory and practical.

TheoryIn the theory portion of each course, students independently research subjects prior to entering the

classroom for discussion. At the start of the classroom session, the instructor will check each student’spreparation using one of several methods (direct inspection of work, a pop quiz, targeted questions, etc.).Students then spend some class time working in small groups coordinating their presentations. The rest ofthe class time is spent interacting Socratically with the instructor in a large-group dialogue. The instructorcalls students (or student groups) to present what they found in their research, questions that arose duringtheir study, their solutions to problems, and any problem-solving techniques applied. The instructor’s roleis to help students take the information gleaned from their research and convert this into understanding.

LabIn the lab portion of each course, students work in teams to install, configure, document, calibrate, and

troubleshoot working instrument loop systems. Each lab exercise focuses on a different type of instrument,with a eight-day period typically allotted for completion. An ordinary lab session might look like this:

(1) Start of practical (lab) session: announcements and planning(a) Instructor makes general announcements to all students(b) Instructor works with team to plan that day’s goals, making sure each team member has a clear

idea of what they should accomplish(2) Teams work on lab unit completion according to recommended schedule:

(First day) Select and bench-test instrument(s)(One day) Connect instrument(s) into a complete loop(One day) Each team member drafts their own loop documentation, inspection done as a team (withinstructor)(One or two days) Each team member calibrates/configures the instrument(s)(Remaining days, up to last) Each team member troubleshoots the instrument loop(Last day) All teams answer lab questions, one team at a time, with the instructor

(3) End of practical (lab) session: debriefing where each team reports on their work to the whole class

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Distance delivery methods

Sometimes the demands of life prevent students from attending college 6 hours per day. In such cases,there exist alternatives to the normal 8:00 AM to 3:00 PM class/lab schedule, allowing students to completecoursework in non-traditional ways, at a “distance” from the college campus proper.

For such “distance” students, the same worksheets, lab activities, exams, and academic standards stillapply. Instead of working in small groups and in teams to complete theory and lab sections, though, studentsparticipating in an alternative fashion must do all the work themselves. Participation via teleconferencing,video- or audio-recorded small-group sessions, and such is encouraged and supported.

There is no recording of hours attended or tardiness for students participating in this manner. The paceof the course is likewise determined by the “distance” student. Experience has shown that it is a benefit for“distance” students to maintain the same pace as their on-campus classmates whenever possible.

In lieu of small-group activities and class discussions, comprehension of the theory portion of each coursewill be ensured by completing and submitting detailed answers for all worksheet questions, not just passingdaily quizzes as is the standard for conventional students. The instructor will discuss any incomplete and/orincorrect worksheet answers with the student, and ask that those questions be re-answered by the studentto correct any misunderstandings before moving on.

Labwork is perhaps the most difficult portion of the curriculum for a “distance” student to complete,since the equipment used in Instrumentation is typically too large and expensive to leave the school labfacility. “Distance” students must find a way to complete the required lab activities, either by arrangingtime in the school lab facility and/or completing activities on equivalent equipment outside of school (e.g.at their place of employment, if applicable). Labwork completed outside of school must be validated by asupervisor and/or documented via photograph or videorecording.

Conventional students may opt to switch to “distance” mode at any time. This has proven to be abenefit to students whose lives are disrupted by catastrophic events. Likewise, “distance” students mayswitch back to conventional mode if and when their schedules permit. Although the existence of alternativemodes of student participation is a great benefit for students with challenging schedules, it requires a greaterinvestment of time and a greater level of self-discipline than the traditional mode where the student attendsschool for 6 hours every day. No student should consider the “distance” mode of learning a way to havemore free time to themselves, because they will actually spend more time engaged in the coursework thanif they attend school on a regular schedule. It exists merely for the sake of those who cannot attend duringregular school hours, as an alternative to course withdrawal.

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General advice for successful learning

Reserve a time and a place for study• Schedule a block of time every day for study and make it a priority!• Create or join a study group, and help each other commit to regular study time.• Keep the environment of your study place ideal: whatever music (or no music) helps you concentrate,

whatever time allows for the least number of distractions, etc.• Plan to arrive at school at least a half-hour early and use the time to study as opposed to studying late

at night. This also helps guard against tardiness in the event of unexpected delays, and ensures you abetter parking space!

Who to study with• Classmates with similar schedules.• Classmates who are serious about their education.• Note that the intelligence of your study partners is not a significant criterion!

How to make time for study• Rid yourself of unnecessary, time-wasting gadgets: televisions, video games, mobile phones, etc. I am

not kidding!• Avoid recreational use of the internet.• Bring a meal to school every day and use your one-hour lunch break for study instead of eating out.• Carefully plan your lab sessions with your teammates to reserve a portion of each day’s lab time for

study.• Cut off all unhealthy personal relationships.

Make efficient use of the time you have• Do not procrastinate, waiting until the last minute to do something.• Don’t let small chunks of time at home or at school go to waste. Work a little bit on assignments during

these times.• Identify menial chores you can do simultaneously (e.g. house cleaning and laundry), and plan your

chore time accordingly to free up more time at home.

Take responsibility for your learning and your life• Obtain all the required books, and any supplementary study materials available to you. If the books

cost too much, look on the internet for used texts (www.amazon.com, www.half.com, etc.) and use themoney from the sale of your television and video games to buy them!

• Make an honest attempt to solve problems before asking someone else to help you. Being able toproblem-solve is a skill that will improve only if you continue to do work at it.

• If you detect trouble understanding a basic concept, seek clarification on it immediately. Never ignorean area of confusion, believing you will pick up on it later. Later may be too late!

• Do not wait for others to do things for you. No one is going to make extra effort purely on your behalf.• Seek help for any addictions. Addictions won’t just destroy your chance at an education – they can

destroy your whole life!

. . . And the number one tip for success . . .• Realize that there are no shortcuts to learning. Every time you seek a shortcut, you are actually cheating

yourself out of a learning opportunity!!

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Creative Commons License

This worksheet is licensed under the Creative Commons Attribution License, version 1.0. To viewa copy of this license, visit http://creativecommons.org/licenses/by/1.0/ or send a letter to CreativeCommons, 559 Nathan Abbott Way, Stanford, California 94305, USA. The terms and conditions of thislicense allow for free copying, distribution, and/or modification of all licensed works by the general public.

Simple explanation of Attribution License:

The licensor (Tony Kuphaldt) permits others to copy, distribute, display, and otherwise use thiswork. In return, licensees must give the original author(s) credit. For the full license text, please visithttp://creativecommons.org/licenses/by/1.0/ on the internet.

More detailed explanation of Attribution License:

Under the terms and conditions of the Creative Commons Attribution License, you may make freelyuse, make copies, and even modify these worksheets (and the individual “source” files comprising them)without having to ask me (the author and licensor) for permission. The one thing you must do is properlycredit my original authorship. Basically, this protects my efforts against plagiarism without hindering theend-user as would normally be the case under full copyright protection. This gives educators a great dealof freedom in how they might adapt my learning materials to their unique needs, removing all financial andlegal barriers which would normally hinder if not prevent creative use.

Nothing in the License prohibits the sale of original or adapted materials by others. You are free tocopy what I have created, modify them if you please (or not), and then sell them at any price. Once again,the only catch is that you must give proper credit to myself as the original author and licensor. Given thatthese worksheets will be continually made available on the internet for free download, though, few peoplewill pay for what you are selling unless you have somehow added value.

Nothing in the License prohibits the application of a more restrictive license (or no license at all) toderivative works. This means you can add your own content to that which I have made, and then exercisefull copyright restriction over the new (derivative) work, choosing not to release your additions under thesame free and open terms. An example of where you might wish to do this is if you are a teacher who desiresto add a detailed “answer key” for your own benefit but not to make this answer key available to anyoneelse (e.g. students).

Note: the text on this page is not a license. It is simply a handy reference for understanding the LegalCode (the full license) - it is a human-readable expression of some of its key terms. Think of it as theuser-friendly interface to the Legal Code beneath. This simple explanation itself has no legal value, and itscontents do not appear in the actual license.

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Metric prefixes and conversion constants

• Metric prefixes

• Yotta = 1024 Symbol: Y

• Zeta = 1021 Symbol: Z

• Exa = 1018 Symbol: E

• Peta = 1015 Symbol: P

• Tera = 1012 Symbol: T

• Giga = 109 Symbol: G

• Mega = 106 Symbol: M

• Kilo = 103 Symbol: k

• Hecto = 102 Symbol: h

• Deca = 101 Symbol: da

• Deci = 10−1 Symbol: d

• Centi = 10−2 Symbol: c

• Milli = 10−3 Symbol: m

• Micro = 10−6 Symbol: µ

• Nano = 10−9 Symbol: n

• Pico = 10−12 Symbol: p

• Femto = 10−15 Symbol: f

• Atto = 10−18 Symbol: a

• Zepto = 10−21 Symbol: z

• Yocto = 10−24 Symbol: y

1001031061091012 10-3 10-6 10-9 10-12(none)kilomegagigatera milli micro nano pico

kMGT m µ n p

10-210-1101102

deci centidecahectoh da d c

METRIC PREFIX SCALE

• Conversion formulae for temperature

• oF = (oC)(9/5) + 32

• oC = (oF - 32)(5/9)

• oR = oF + 459.67

• K = oC + 273.15

Conversion equivalencies for distance

1 inch (in) = 2.540000 centimeter (cm)

1 foot (ft) = 12 inches (in)

1 yard (yd) = 3 feet (ft)

1 mile (mi) = 5280 feet (ft)

14

Conversion equivalencies for volume

1 gallon (gal) = 231.0 cubic inches (in3) = 4 quarts (qt) = 8 pints (pt) = 128 fluid ounces (fl. oz.)= 3.7854 liters (l)

1 milliliter (ml) = 1 cubic centimeter (cm3)

Conversion equivalencies for velocity

1 mile per hour (mi/h) = 88 feet per minute (ft/m) = 1.46667 feet per second (ft/s) = 1.60934kilometer per hour (km/h) = 0.44704 meter per second (m/s) = 0.868976 knot (knot – international)

Conversion equivalencies for mass

1 pound (lbm) = 0.45359 kilogram (kg) = 0.031081 slugs

Conversion equivalencies for force

1 pound-force (lbf) = 4.44822 newton (N)

Conversion equivalencies for area

1 acre = 43560 square feet (ft2) = 4840 square yards (yd2) = 4046.86 square meters (m2)

Conversion equivalencies for common pressure units (either all gauge or all absolute)

1 pound per square inch (PSI) = 2.03602 inches of mercury (in. Hg) = 27.6799 inches of water (in.W.C.) = 6.894757 kilo-pascals (kPa) = 0.06894757 bar

1 bar = 100 kilo-pascals (kPa)

Conversion equivalencies for absolute pressure units (only)

1 atmosphere (Atm) = 14.7 pounds per square inch absolute (PSIA) = 101.325 kilo-pascals absolute(kPaA) = 1.01325 bar (bar) = 760 millimeters of mercury absolute (mmHgA) = 760 torr (torr)

Conversion equivalencies for energy or work

1 british thermal unit (Btu – “International Table”) = 251.996 calories (cal – “International Table”)= 1055.06 joules (J) = 1055.06 watt-seconds (W-s) = 0.293071 watt-hour (W-hr) = 1.05506 x 1010

ergs (erg) = 778.169 foot-pound-force (ft-lbf)

Conversion equivalencies for power

1 horsepower (hp – 550 ft-lbf/s) = 745.7 watts (W) = 2544.43 british thermal units per hour(Btu/hr) = 0.0760181 boiler horsepower (hp – boiler)

Acceleration of gravity (free fall), Earth standard

9.806650 meters per second per second (m/s2) = 32.1740 feet per second per second (ft/s2)

15

Physical constants

Speed of light in a vacuum (c) = 2.9979 × 108 meters per second (m/s) = 186,281 miles per second(mi/s)

Avogadro’s number (NA) = 6.022 × 1023 per mole (mol−1)

Electronic charge (e) = 1.602 × 10−19 Coulomb (C)

Boltzmann’s constant (k) = 1.38 × 10−23 Joules per Kelvin (J/K)

Stefan-Boltzmann constant (σ) = 5.67 × 10−8 Watts per square meter-Kelvin4 (W/m2·K4)

Molar gas constant (R) = 8.314 Joules per mole-Kelvin (J/mol-K)

Properties of Water

Freezing point at sea level = 32oF = 0oC

Boiling point at sea level = 212oF = 100oC

Density of water at 4oC = 1000 kg/m3 = 1 g/cm3 = 1 kg/liter = 62.428 lb/ft3 = 1.94 slugs/ft3

Specific heat of water at 14oC = 1.00002 calories/g·oC = 1 BTU/lb·oF = 4.1869 Joules/g·oC

Specific heat of ice ≈ 0.5 calories/g·oC

Specific heat of steam ≈ 0.48 calories/g·oC

Absolute viscosity of water at 20oC = 1.0019 centipoise (cp) = 0.0010019 Pascal-seconds (Pa·s)

Surface tension of water (in contact with air) at 18oC = 73.05 dynes/cm

pH of pure water at 25o C = 7.0 (pH scale = 0 to 14)

Properties of Dry Air at sea level

Density of dry air at 20oC and 760 torr = 1.204 mg/cm3 = 1.204 kg/m3 = 0.075 lb/ft3 = 0.00235slugs/ft3

Absolute viscosity of dry air at 20oC and 760 torr = 0.018 centipoise (cp) = 1.8 × 10−5 Pascal-seconds (Pa·s)

file conversion constants

16

Question 0

How to read actively:

• Make notes in a notebook while reading – if you’re not “reading with a pencil,” you’re not activelyreading! “Shorthand” notation, diagrams, and other notes jotted in a notebook are more effective atprompting active reading than underlining, highlighting, or otherwise marking up the original text.

• Mentally summarize each new concept or application you encounter in your own words before movingon to the next. If you cannot do this, you know you need to re-read the relevant sections until you can!

• Try to link new concepts to previously-learned concepts, and imagine how new concepts might apply toapplications not mentioned in the text. Make notes on these points so you may raise them as questionsduring class time.

• Note page numbers where important concepts, equations, images, tables, and problem-solving techniquesare introduced This will help you locate these important references during class time when you willcontribute in the dicsussion (“On page 572 it shows . . .”).

• Note page numbers of any sections in the reading that confound you, so you may call attention to it atthe start of class time to get help from classmates and/or the instructor.

• If the text demonstrates a mathematical calculation, such as how to apply a new equation to solving aproblem, pick up your calculator and work through the example as you read! Applications of math arean ideal opportunity to actively read a technical book, actually engaging in the material rather thanpassively observing what it says.

• Reserve the front pages of your notebook (or keep a separate notebook) for all mathematical formulaeyou come across in your reading. Briefly explain in your own words what each formula does and whatits terms mean.

Problem-solving techniques

• Clearly identify all “given” information, and also what the question is asking you to determine or solve.

• Sketch a diagram or graph to organize all the “given” information and show where the answer will fit.

• Performing “thought experiments” to visualize the effects of different conditions.

• Working “backward” from a hypothetical solution to a new set of given conditions.

• Changing the problem to make it simpler, and then solving the simplified problem (e.g. changingquantitative to qualitative, or visa-versa; substituting different numerical values to make them easierto work with; eliminating confusing details; adding details to eliminate unknowns; considering limitingcases that are easier to grasp).

• Identify any “first principles” of science, electronics, and/or instrumentation (e.g. Conservation laws,Feedback, Zero and Span, Ohm’s Law, etc.) that might apply to the question.

• Specifically identify which portion(s) of the question you find most confusing and need help with. Themore specific you are able to be, the better.

file question0

17

Questions

Question 1

Lightly read the “Continuous Temperature Measurement” chapter in your Lessons In IndustrialInstrumentation textbook and answer the following questions:

Explain how a bi-metal strip works as a temperature-sensing device.

A common mechanic’s “trick” for slipping a metal bearing or ring over a metal shaft where the two partswould ordinarily make a very tight fit, is to either heat the ring and/or freeze the shaft prior to assembly.Explain why this “trick” works in light of what you know about coefficients of expansion.

A ring made of copper tightly fitted over an iron shaft may be more easily removed from the shaft ifboth are first heated. However, a copper ring tightly fit over an aluminum shaft will not loosen up when boththe ring and shaft are heated. Referencing the coefficients of thermal expansion for these metals, explainwhy.

file i03971

Question 2


Explain how a metal bulb filled with fluid may act as a temperature-sensing device.

Identify some of the common “classes” of filled-bulb temperature sensors, and describe the differencesbetween them.

file i03972

18

Question 3

A filled-system temperature indicator is calibrated in the instrument shop with the sensing bulb atthe same level (height) as the bourdon tube indicating element. In the field, however, the sensing bulb issignificantly elevated from the bourdon tube’s height.

oF

When calibrated

oF

Wheninstalled

Will this cause a measurement error? If so, what type of error (zero or span shift) will it be?file i00360

Question 4


Both thermistors and RTDs are electrically-based temperature sensors. Identify the electrical propertyof each that changes with temperature.

Explain how you would use common electrical test equipment (such as that found in any electronicsworkshop or laboratory) to check whether or not a thermistor or an RTD is functional.

file i03973

Question 5


Thermocouples are a type of electrically-based temperature sensor. Identify the electrical property of athermocouple that changes with temperature.

Explain how you would use common electrical test equipment (such as that found in any electronicsworkshop or laboratory) to check whether or not a thermocouple is functional.

file i03974

19

Question 6


Explain how the temperature of an object may be sensed optically (non-contact).

Identify some practical applications of non-contact temperature measurement, as well as somedisadvantages (compared to direct-contact methods of temperature measurement).

file i03975

Question 7


Describe what a thermowell is, what function it performs, and what one looks like.

Identify some of the temperature measurement problems that may result from improperly using athermowell.

file i03976

Question 8

The formula for converting degrees Celsius into degrees Fahrenheit is as follows:

oF =

(

9

5

)

oC + 32

Use algebra to manipulate this equation to solve for degrees Celsius.file i00344

Question 9

Convert between the following units of temperature:

• 300o C = ???o F

• 50o F = ???o C

• 4o C = ???o F

• 894o F = ???o C

• -250o F = ???o C

• -312o F = ???o C

• -150o C = ???o F

• -230o C = ???o F

• 2600o F = ???o C

• 3000o C = ???o F

file i00339

20

Question 10

A student needs to convert a temperature value from degrees Fahrenheit to degrees Celsius.Unfortunately, they are not sure of the correct formula. They think the formula goes like this, but they areunsure:

oC =

(

5

9

)

oF − 32

Devise a simple way for this student to test whether or not the formula is correct, without seeking helpfrom a reference document of any kind.

file i00805

Question 11

Read and outline the “Heat Versus Temperature”, “Temperature”, and “Heat” subsections ofthe “Elementary Thermodynamics” section of the “Physics” chapter in your Lessons In IndustrialInstrumentation textbook. Note the page numbers where important illustrations, photographs, equations,tables, and other relevant details are found. Prepare to thoughtfully discuss with your instructor andclassmates the concepts and examples explored in this reading.

file i03977

Question 12

It is common for physicists to categorize matter in one of four different “phases:” solid, liquid, gas, andplasma. Define what each of these four phases is, and also what “phase change” refers to.

file i00347

Question 13

In a filled-system type of temperature instrument, why is it important to use a small-diameter(“capillary”) tube to connect the bulb to the bellows? Why not use regular, large-diameter tubing instead?

file i00358

21

Question 14

Identify the following filled-system types (be as specific as possible – each system shown here has aunique identifying name!).

Bellows

ScalePointer

Liquid

Liquid

Bulb

Pivot

Bellows

Bulb

Pivot

Gas

Gas

ScalePointer

Bellows

ScalePointer

Bulb

Pivot

Bellows

Bulb

Pivot ScalePointer

Vapor

Vapor

Vapor

Volatileliquid

Volatileliquid

Volatileliquid

22

Bellows

ScalePointer

Bulb

Pivot

Bellows

Bulb

Pivot ScalePointer

Vapor

Gas

Volatile liquid

Nonvolatileliquid

Nonvolatileliquid

Adsorptivesolid

file i00359

Question 15

Explain what the following “ladder-logic” circuit does, and identify the meaning of each symbol in thediagram:

L1 L2

TSH

TSL

Temp. high

Temp. low

TSHH

Cooling watersolenoid

file i00364

Question 16

Question 17

Question 18

23

Question 19

Question 20

Question 21

Read and outline the “Heat Transfer” subsection of the “Elementary Thermodynamics” section of the“Physics” chapter in your Lessons In Industrial Instrumentation textbook. Note the page numbers whereimportant illustrations, photographs, equations, tables, and other relevant details are found. Prepare tothoughtfully discuss with your instructor and classmates the concepts and examples explored in this reading.

file i03978

Question 22

The R-value of an insulating material is defined as the quotient of length (l) and thermal conductivity(k), both from the heat conduction equation:

R =l

k

dQ

dt=

kA∆T

l

Modify the heat conduction equation to incorporate R instead of k, and then use it to calculate theheat loss rate through the surfaces of the following box, insulated with R-30 insulation (R = 30 ft2 · h · Fo /Btu), heated internally to a temperature of 75o F, and exposed to an outside (ambient) temperature of 40o

F:

10 ft

10 ft

10 ft

Challenge question: if the box is heated solely by an electric light bulb, how many watts would this lightbulb have to be in order to maintain an internal box temperature of 75o F given an outside temperature of40o F?

file i00333

Question 23

Read and outline the “Specific Heat and Enthalpy” subsection of the “Elementary Thermodynamics”section of the “Physics” chapter in your Lessons In Industrial Instrumentation textbook. Note the pagenumbers where important illustrations, photographs, equations, tables, and other relevant details are found.Prepare to thoughtfully discuss with your instructor and classmates the concepts and examples explored inthis reading.

file i03979

24

Question 24

Suppose you own a hot tub holding 700 gallons of water, with water weighing approximately 8.3 poundsper gallon. Calculate the amount of thermal energy (in units of BTUs) necessary to raise the temperatureof the water in the hot tub from ambient (60 degrees Fahrenheit) to 100 degrees Fahrenheit, assuming noheat lost to the surrounding environment in the process.

Calculate the cost of initially heating this hot tub with propane gas, assuming a propane rate of $2.20per gallon, a heating value of 21,700 BTU per pound of propane, and a propane density of 4.2 pounds pergallon.

Calculate the cost of initially heating this hot tub with electricity, assuming an electrical power rate of8.5 cents per kilowatt-hour.

file i03980

Question 25

Read and outline the “Phase Changes” subsection of the “Elementary Thermodynamics” section ofthe “Physics” chapter in your Lessons In Industrial Instrumentation textbook. Note the page numberswhere important illustrations, photographs, equations, tables, and other relevant details are found. Prepareto thoughtfully discuss with your instructor and classmates the concepts and examples explored in thisreading.

file i03981

Question 26

Calculate the amount of heat energy released by two pounds of steam as it cools from 250 oF to 125 oF,in units of BTU. Be sure to separate your solution into three steps: the heat lost as the steam cools to thecondensing temperature (212 oF), the latent heat released through condensation, and the heat lost as thecondensed water cools to the final temperature.

In which step of this three-step heat loss process is most of the heat being released? What does thisindicate about the heat-storing capabilities of water, steam, and phase changes between water and steam?

file i03982

Question 27


• 350 K = ???o C

• 575o F = ???o R

• -210o C = ??? K

• 900o R = ???o F

• -366o F = ???o R

• 100 K = ???o C

• 2888o C = ??? K

• 4502o R = ???o F

• 1000 K = ???o R

• 3000o R = ??? K

file i00340

25

Question 28


• 235o C = ???o R

• 567.2o F = ??? K

• 0.004 K = ???o F

• 830o R = ???o C

• -200o C = ???o R

• -98.25o F = ??? K

• 992.8o C = ???o F

• -105.3o C = ???o F

• 1040 K = ???o R

• 5222.6o R = ???o C

file i00341

Question 29

A very useful principle in physics is the Ideal Gas Law, so called because it relates pressure, volume,molecular quantity, and temperature of an ideal gas together in one neat mathematical expression:

PV = nRT

Where,P = Absolute pressure (atmospheres)V = Volume (liters)n = Gas quantity (moles)R = Universal gas constant (0.0821 L · atm / mol · K)T = Absolute temperature (K)

Note that temperature T in this equation must be in absolute units (Kelvin). Modify the Ideal Gas Lawequation to accept a value for T in units of oC.

Then, modify the equation once more to accept a value for T in units of oF.file i00342

26

Question 30

The rate of heat transfer through radiation from a warm body may be expressed by the Stefan-Boltzmannequation:

dQ

dt= eσAT 4

Where,dQdt

= Rate of heat flowe = Emissivity factorσ = Stefan-Boltzmann constant (5.67 × 10−8 W / m2 · K4)A = Area of radiating surfaceT = Absolute temperature

Based on the unit of measurement given for the Stefan-Boltzmann constant, determine the proper unitsof measurement for heat flow, emissivity, area, and temperature.

file i00343

27

Question 31

Solids tend to expand when heated. The amount a solid sample will expand with increased temperaturedepends on the size of the sample and the material it is made of. A formula expressing linear expansion inrelation to temperature is as follows:

l = l0(1 + α∆T )

Where,l = Length of material after heatingl0 = Original length of materialα = Coefficient of linear expansion∆T = Change in temperature

Here are some typical values of α for common metals:

• Aluminum = 25 × 10−6 per degree C• Copper = 16.6 × 10−6 per degree C• Iron = 12 × 10−6 per degree C• Tin = 20 × 10−6 per degree C• Titanium = 8.5 × 10−6 per degree C

We may also express the tendency for the area and the volume of a solid to expand when heated, notjust its linear dimensions. If we imagine a square with original length l0 and original width l0, the originalarea of the square must be l0

2, which means the new area of the square after heating will be:

A = [l0(1 + α∆T )]2

A = l20(1 + α∆T )2

A = l20(1 + α∆T )(1 + α∆T )

A = l20[1 + 2α∆T + (α∆T )2]

or

A = A0[1 + 2α∆T + (α∆T )2]

This equation may be simplified by approximation – a mathematical principle commonly applied inelectrical engineering known as swamping:

A ≈ A0(1 + 2α∆T )

Explain why it is okay to make this simplification, and extrapolate the principle to calculating the newvolume of a solid material after heating.

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28

Question 32

Suppose that a liquid is placed into a container, and then all the air is drawn out of that container usinga vacuum pump:

Liquid

Pump

Air being removedfrom container

The container is then sealed, and the absolute pressure measured with some kind of pressure instrument:

Liquid

Pabsolute

As the liquid is trapped inside the container, thermal energy liberates some of the molecules into thevacuum above, resulting in a vapor forming above the liquid. As some of these vapor molecules strike thewalls of the container, they condense back into liquid and dribble down into the liquid pool below. When therates of evaporation and condensation reach equilibrium, we say the liquid/vapor process is in a conditionof saturation, and the amount of pressure inside this vessel as the saturated vapor pressure of the substance.“Saturated” simply refers to the condition where the rates of evaporation and condensation exactly match;when the space above the liquid can hold no more vapor molecules.

Suppose we now attach a piston to this container so we may change the volume of the vapor space:

29

Liquid

Pabsolute

Piston

If the system reaches a state of saturation (evaporation and condensation rates equal), and temperatureremains the same, what will happen to the pressure in the container if the piston is moved inward, thusdecreasing volume? Does the pressure increase, decrease, or stay the same?

Now suppose we attach a pump to the bottom of this container so we may remove some of the liquidwithout letting any air in:

Pabsolute

Piston

DischargePumpLiquid

If the system reaches a state of saturation (evaporation and condensation rates equal), and temperatureremains the same, what will happen to the pressure in the container as liquid is drawn out? Does thepressure increase, decrease, or stay the same?

file i00348

30

Question 33

A propane tank holds both liquid propane and propane vapor at high pressure:

Liquidpropane

Propanevapor

How may the pressure in the tank be altered? What physical variable must be changed in order toincrease or decrease the vapor pressure inside the tank?

file i00349

Question 34

Rank the following transitions according to the amount of heat energy input required:

• To heat a pound of water from 60o F to 65o F.• To boil a pound of water completely into steam (warming it from 211o F to 213o F).• To melt a pound of ice completely into water (warming it from 31o F to 33o F).

file i00353

Question 35

An instrument technician wants to create a temperature reference for a thermocouple transmitter byfreezing some water, knowing that the freezing point of water at sea level is 32o F (or 0o C). He inserts thethermocouple into a cup of water, then sets the cup and thermocouple inside a freezer until the water isfrozen solid. He then takes the cup out of the freezer and connects the thermocouple to the temperaturetransmitter for calibration.

What is wrong with the technician’s procedure? What must be done differently to ensure a referencetemperature of 32o F (0o C) at the thermocouple tip?

file i00355

31

Question 36

Suppose an empty test vessel of fixed volume is immersed in an ice-water mixture and allowed tostabilize at that temperature, with a bleed valve left open to equalize the vessel’s air pressure with ambient(atmospheric) pressure at sea level:

Ice/water mix

Vessel

Once stabilized, the valve is shut off and the vessel is taken out of the ice-water bath, then left tostabilize at room temperature (70o F). Calculate the pressure built up inside the vessel resulting from theincreased temperature, in units of inches water column (”W.C.).

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32

Question 37

An absolute pressure gauge is connected to a hollow metal sphere containing a gas:

sphere

Absolute pressure gauge

Hollow

According to the Ideal Gas Law, the relationship between the gauge’s pressure indication and thesphere’s temperature is as follows:

PV = nRT

Unfortunately, though, we do not happen to know the volume of the sphere (V ) or the number ofmoles of gas contained within (n). At best, all we can do is express the relationship between P and T asa proportionality, or as an equality with a constant of proportionality (k) accounting for all the unknownvariables and unit conversions:

P ∝ T P = kT

Calculate the value of this constant (k) if you happen to know that the pressure gauge registers 1.5 barat a temperature of 280 K. Then, predict the temperature when the pressure gauge reads 1.96 bar.

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33

Question 38

A physics professor wants to demonstrate the Ideal Gas Law to his students, so he builds an apparatusconsisting of a hollow metal sphere, a small-diameter tube, a bleed valve, and a pressure gauge that lookslike this:

bleed

sphere

tube

First, he immerses the sphere in an ice-water mixture to set the air temperature inside the sphere to 0o

C (273.15 K), leaving the bleed valve open to equalize the air pressure inside the sphere with atmospheric.Next, he closes off the bleed valve to trap air inside the system and plunges the sphere into a beaker fullof boiling water (100o C, or 373.15 K). The pressure gauge indication rises, of course, but it does not fullyreach the pressure calculated by the professor using the Ideal Gas Law, even after being left immersed inthe boiling water for some time.

Calculate the “hot” pressure using the Ideal Gas Law, and express it in units of PSIG. Also, explainwhy the pressure registered by the gauge will never be quite as large as that predicted by the Law.

file i02971

Question 39

Question 40

Question 41

Read and outline the “Temperature Coefficient of Resistance (α)” subsection of the “Thermistorsand Resistance Temperature Detectors (RTDs)” section of the “Continuous Temperature Measurement”chapter in your Lessons In Industrial Instrumentation textbook. Note the page numbers where importantillustrations, photographs, equations, tables, and other relevant details are found. Prepare to thoughtfullydiscuss with your instructor and classmates the concepts and examples explored in this reading.

file i03984

Question 42

A platinum RTD with an R0 of 1000 Ω and an α = 0.00392 Ω/Ω·oC is heated to a temperature of 120o

C. Calculate its resistance at that temperature.

Also, calculate the temperature of the same RTD if its resistance measures 1043.8 Ω.file i00406

34

Question 43

A 100 Ω platinum RTD with an alpha (α) of 0.00385 has a measured resistance of 98 Ω. Calculate itstemperature, expressing your answer both in degrees C and degrees F.

file i00407

Question 44

Read and outline the “Two-Wire RTD Circuits”, “Four-Wire RTD Circuits”, and “Three-Wire RTDCircuits” subsections of the “Thermistors and Resistance Temperature Detectors (RTDs)” section of the“Continuous Temperature Measurement” chapter in your Lessons In Industrial Instrumentation textbook.Note the page numbers where important illustrations, photographs, equations, tables, and other relevantdetails are found. Prepare to thoughtfully discuss with your instructor and classmates the concepts andexamples explored in this reading.

file i03985

Question 45

Draw schematic diagrams for the following RTDs:

BlkBlk

Red RedWht

WhtRed

file i00404

35

Question 46

Calculate the output voltage of this bridge circuit at the following RTD temperatures (assume the useof a 100 Ω RTD with a European alpha value).

RTD

100 Ω

100 Ω

100 Ω50 mV

Vout+−excitation

source

• Vout = at T = 0o C


• Vout = at T = -15o C

file i00410

Question 47

Choose proper resistor values so that the op-amp outputs a 0 to 5 volt voltage signal over a temperaturemeasurement range of 0o C to 80o C. Assume the use of a 1000 Ω RTD with a European alpha.

RTD1 kΩ

−

+1 V

Temperature range = 0o C to 80o C

European α

Vout

Vout = 0 to 5 volts

+−

file i00411

36

Question 48

Shown here is a typical 2-wire RTD circuit, where the RTD is located a considerable distance away fromthe bridge circuit:

RTD

100 Ω

100 Ω

100 Ω

50 mV

100 Ω

Rwire = 2 Ω

Rwire = 2 Ω

+− Vout

The two-wire cable connecting the RTD to the rest of the bridge circuit has resistance distributed alongits length, shown in the schematic in “lumped” form as two “Rwire” resistors. What effect will the presenceof this cable resistance have on the temperature measurement system? Will it result in a zero shift, a spanshift, or both? Why??

Calculate the output voltage of this bridge circuit when the 100 Ω RTD is at its reference temperatureof 0o C, and each Rwire resistance is equal to 2 Ω (Hint: the alpha figure is irrelevant in this problem).

Also calculate how hot the RTD “appears” to be as indicated by the output voltage of the bridge circuit,given the added cable resistance. Assume a European α value for this calculation.

file i00413

Question 49

Shown here is a typical 3-wire RTD circuit, where the RTD is located a considerable distance away fromthe bridge circuit:

RTD

100 Ω

100 Ω

100 Ω

50 mVRwire

Rwire

100 Ω

Rwire

+− Vout

Calculate the output voltage of this bridge circuit when the 100 Ω RTD is at its reference temperatureof 0o C, and each Rwire resistance is equal to 2 Ω (Hint: the alpha figure is irrelevant in this problem):

Comment on how this 3-wire RTD circuit compares against a 2-wire RTD circuit with the same amountof cable resistance.

file i00414

37

Question 50

Explain why this 4-wire RTD circuit is completely immune to calibration drift resulting from cableresistance:

RTD100 Ω

Rwire = 2 Ω

Rwire = 2 Ω

Vout

Rwire = 2 Ω

Rwire = 2 Ω

Also, identify the polarity of the voltage dropped across the output terminals.file i00415

Question 51

A typical RTD specification reads as such: 100 Ω platinum @ 0o C, alpha = 0.00385 Ω/Ω·oC. What,exactly, does this statement mean?

file i00405

Question 52

Some RTDs have an alpha value of 0.00392 Ω/Ω·o C, while some others have an alpha value of 0.00385Ω/Ω/o C. Which of these alpha values is typically associated with European manufacturers and which istypically associated with American manufacturers?

file i00408

Question 53

In this circuit, a thermistor is used to control power to a lamp:

-to

As the temperature increases, does the lamp become brighter or dimmer? Explain your answer.file i00417

38

Question 54

A basic circuit often used to regulate current through a variable-resistance load is the classic currentmirror:

Rprg Rload

Current mirror sourcingconstant current to

a varying load resistance

+V +V

The “programming” resistor (Rprg) establishes the current magnitude to be maintained through thevarying-resistance load, in this case an RTD or a thermistor. For optimum performance, the two transistorsshould be precisely matched and also share the same heat sink (or be etched on the same semiconductorsubstrate).

However, we can do much better than this circuit if we use an operational amplifier. Consider this“modernized” current mirror circuit:

+V

Rload

−+Rprg

R1 R2

Here there is no need for matched transistors or special heat-sinking. So long as resistors R1 and R2

have equal resistance, the current through Rload will be maintained at the same value as the current throughRprg. If the intended current value is large, we may “boost” the output of the opamp with a single transistor:

39

+V

Rload

−+Rprg

R1 R2

+V

Explain how both of these operational amplifier circuits work, and why they function as “currentmirrors.”

file i00418

Question 55

Calculate the output voltage of this bridge circuit at the following RTD temperatures (assume the useof a 100 Ω RTD with an American alpha value).

RTD

100 Ω

100 Ω

100 Ω

Vout+−excitation

source

100 mV

• Vout = at T = -20o C



file i00690

40

Question 56

Calculate Vout in this 4-wire RTD circuit when the temperature of the RTD is 135o F (assume anAmerican α value):

RTD100 ΩVout800 µA

Rwire = 3 Ω

Rwire = 3 Ω

Rwire = 3 Ω

Rwire = 3 Ω

file i00691

41

Question 57

Plot a graph of an RTD’s resistance over a temperature range of 0o C to 200o C. Assume a 100 Ω RTDwith an American alpha value.

0o C 200o C

Ω

Then, plot a graph of a bridge circuit’s voltage output containing the same RTD (100 Ω, American α),as its temperature changes from 0o C to 200o C:

RTD

100 Ω

100 Ω

100 Ω

50 mV +− Vout

0o C 200o C

mV

Compare these two graphs, then comment on the behavior of RTDs both inside and outside of a bridgecircuit.

42

file i00412

Question 58

One of the potential problems with using an RTD to measure temperature is something called self-heating. This problem affects all temperature-sensing elements that are externally powered. By contrast,thermocouples do not suffer this problem. Explain what the problem of self-heating is, how it may bemitigated for RTDs, and why thermocouples do not suffer from it.

file i00806

Question 59

Question 60

Question 61

Read and outline the “Dissimilar Metal Junctions” subsection of the “Thermocouples” section of the“Continuous Temperature Measurement” chapter in your Lessons In Industrial Instrumentation textbook.Note the page numbers where important illustrations, photographs, equations, tables, and other relevantdetails are found. Prepare to thoughtfully discuss with your instructor and classmates the concepts andexamples explored in this reading.

file i03986

Question 62

Read and outline the “Thermocouple Types” subsection of the “Thermocouples” section of the“Continuous Temperature Measurement” chapter in your Lessons In Industrial Instrumentation textbook.Note the page numbers where important illustrations, photographs, equations, tables, and other relevantdetails are found. Prepare to thoughtfully discuss with your instructor and classmates the concepts andexamples explored in this reading.

file i03987

Question 63

Read and outline the “Connector and Tip Styles” subsection of the “Thermocouples” section of the“Continuous Temperature Measurement” chapter in your Lessons In Industrial Instrumentation textbook.Note the page numbers where important illustrations, photographs, equations, tables, and other relevantdetails are found. Prepare to thoughtfully discuss with your instructor and classmates the concepts andexamples explored in this reading.

file i03988

Question 64

Read and outline the “Manually Interpreting Thermocouple Voltages” subsection of the“Thermocouples” section of the “Continuous Temperature Measurement” chapter in your Lessons InIndustrial Instrumentation textbook. Note the page numbers where important illustrations, photographs,equations, tables, and other relevant details are found. Prepare to thoughtfully discuss with your instructorand classmates the concepts and examples explored in this reading.

file i03989

43

Question 65

Build your own thermocouple by taking a piece of thermocouple cable (type J or K works well) andtwisting together the wires at one end to form a measurement junction. Clip the test leads of a sensitive milli-voltmeter to the other wire ends (the reference junction). Heat the measurement junction using body heator an open flame (e.g. butane lighter) and then use a thermocouple reference table to infer the temperatureof the measurement junction.

file i03629

Question 66

Suppose we use a thermocouple to measure the temperature of a furnace, a voltmeter to indicate thevoltage generated, and we infer furnace temperature from that measured voltage:

Terminal blockFurnace

Instrument roomField

Voltmeter

Thermocouplewire

Copperwire

Describe what will happen to the voltmeter’s indication if the ambient temperature of the instrumentroom increases while the furnace temperature remains the same, and explain why.

file i00371

44

Question 67

A type “T” thermocouple is made of the dissimilar metals copper (Cu) and Constantan (C). Copper isan element while Constantan is an alloy made up of copper and nickel. Thermocouple “tables” published byinstrument manufacturers commonly give measurement junction output voltages for different temperaturesfor an assumed reference junction temperature of 32o F, or 0o C, the freezing point of pure water. Using sucha table, determine the output voltages of a type “T” thermocouple at the following process temperatures:

Voltmeter

Process

C C

CuCuCu

Cu

Ice/water bathTemperature = 32o F = 0o C

• Tprocess = 350o F; Voltmeter voltage = ???• Tprocess = -65o F; Voltmeter voltage = ???• Tprocess = 32o F; Voltmeter voltage = ???• Tprocess = 100o C; Voltmeter voltage = ???

Also determine the standard color codes for type T thermocouple wire:

• Positive conductor:• Negative conductor:• Thermocouple-grade jacket:• Extension-grade jacket:

file i00367

45

Question 68

A type “K” thermocouple is made of the dissimilar metals Chromel (chromium-nickel alloy) andAlumel (aluminum-nickel alloy). Using a thermocouple table, determine the output voltages of a type“K” thermocouple at the following process temperatures:

Voltmeter

Process

Cu

Cu

Temperature = 32o F = 0o C

Chromel

Alumel Alumel

Chromel

Ice/water baths

• Tprocess = 800o F; Voltmeter voltage = ???• Tprocess = -165o F; Voltmeter voltage = ???• Tprocess = 32o F; Voltmeter voltage = ???• Tprocess = 2350o F; Voltmeter voltage = ???

Also determine the standard color codes for type K thermocouple wire:


file i00368

Question 69

Determine the voltmeter’s indication in this thermocouple circuit (type J) for the following temperatures:

VoltmeterCu

Cu

Fe

Type J

Tmeasurement

Treference

Const.

• Tmeasurement = 250o F ; Treference = 60o F ; Voltmeter voltage = ???• Tmeasurement = 733o F ; Treference = 72o F ; Voltmeter voltage = ???• Tmeasurement = -60o F ; Treference = 49o F ; Voltmeter voltage = ???• Tmeasurement = -238o F ; Treference = 80o F ; Voltmeter voltage = ???

file i00380

46

Question 70

Determine the temperature of the measurement junction in this thermocouple circuit (type K), giventhe reference junction temperatures and the voltmeter indications. Round your answer to the nearest wholedegree Fahrenheit:

VoltmeterCu

Cu

Tmeasurement

Treference

Chromel

Alumel

Type K

• Treference = 70o F ; Voltmeter voltage = 20.018 mV ; Tmeasurement = ???• Treference = 65o F ; Voltmeter voltage = 5.833 mV ; Tmeasurement = ???• Treference = 52o F ; Voltmeter voltage = 31.420 mV ; Tmeasurement = ???• Treference = 73o F ; Voltmeter voltage = -2.027 mV; Tmeasurement = ???

file i00382

47

Question 71

It is a fundamental principle of thermocouple circuits that the voltage output by a junction will be thesame as for a collection of isothermal (“same-temperature”) junctions beginning and ending with the samemetal types:

A

Bis equivalent to

A

B

C

D

E

All junctionsat the sametemperature

In other words, a junction comprised of metal A joining together with metal B will produce the samevoltage as a collection of isothermal, series junctions A-C, C-D, D-E, and E-B. This is sometimes referredto as the Law of Intermediate metals.

Apply this equivalence principle to the following circuit, simplifying it so as to reduce the number oftotal junctions to an absolute minimum (assume that you can make the voltmeter wires out of any metaltype you desire, so long as they’re both the same):


Voltmeter

+-

Terminal blockProcess

A

B

C

C

A

B C

B

Would the thermocouple work the same if we got rid of the metal B segment at the terminal block?Explain why or why not.

48


Voltmeter

+-


A

B

A

B C

C

file i00373

Question 72

Are these two thermocouple circuits electrically equivalent? That is, will they produce the samevoltmeter indication given the same temperatures? Why or why not? The abbreviations are as follows:Fe = Iron, C = Constantan, Cu = Copper.

Voltmeter

+-

Process

Fe

C

Fe

C

Cu

Cu

Voltmeter

+-

Process

Fe

C

Fe

C

Fe

Fe

(all conductorsinside voltmeter

made of iron)

(all conductorsinside voltmetermade of copper)

file i00376

49

Question 73

A type “S” thermocouple is made of the dissimilar metals Platinum and Platinum-Rhodium (10%) alloy.Using a thermocouple table, determine the output voltages of a type “S” thermocouple at the followingprocess temperatures:

Voltmeter

Process

Cu

Cu

Temperature = 32o F = 0o CIce/water baths

Pt+10%Rh Pt+10%Rh

Pt Pt

• Voltmeter voltage = 11.857 mV; Tprocess = ???o F• Voltmeter voltage = 6.381 mV; Tprocess = ???o F• Voltmeter voltage = 1.972 mV; Tprocess = ???o F• Voltmeter voltage = 0 mV; Tprocess = ???o F

Also determine the standard color codes for type S thermocouple wire:


file i00369

Question 74

Determine the voltmeter’s indication in this thermocouple circuit (type E) for the followingtemperatures:

VoltmeterCu

CuC

Tmeasurement

Treference

Chromel

Type E

• Tmeasurement = 1500o F ; Treference = 65o F ; Voltmeter voltage = ???• Tmeasurement = 212o F ; Treference = 74o F ; Voltmeter voltage = ???• Tmeasurement = -360o F ; Treference = 32o F ; Voltmeter voltage = ???• Tmeasurement = -132o F ; Treference = -30o F ; Voltmeter voltage = ???

file i00381

50

Question 75

Determine the polarities of all voltage drops across all junctions made of dissimilar metal wires in thefollowing thermocouple circuits:

VoltmeterCu

CuCu

Process

300o F85o F

C (Constantan)

VoltmeterCu

Cu

Process

300o F85o F

C (Constantan)

Fe

file i00375

51

Question 76

How many reference junctions does this thermocouple circuit have?

Yel Red

Type Kthermocouple

(Yellow + Redwires)

YelRed

extension wire extension wire

IndicatorType KX Type KX

file i02972

52

Question 77

Thermocouple wire can be quite expensive in some cases. Suppose a technician is tempted to savemoney, and decides to use a copper wire pair to span the distance between the thermocouple “head” andthe control room where the indicating instrument is located, instead of thermocouple wire or thermocoupleextension wire:

Thermowell

Compressionfitting

Yel Red

Long length of copper cableRed

Blk

Type Kthermocouple

(Red + Black wires)

(Yellow + Redwires)

Furnace wallFurnace wall

Head

Drawn in more of a schematic diagram form, the circuit looks like this:

Terminal blockFurnace


Voltmeter

Thermocouplewire

Copperwire

Explain why this attempt to save money is a bad idea.file i00374

53

Question 78

Is the temperature/resistance transfer function of an RTD more or less linear than thetemperature/voltage transfer function of a thermocouple? What bearing does this have on the decisionto choose a thermocouple versus an RTD for a temperature measurement application?

file i00409

Question 79

Question 80

Question 81

Determine all actions that will result in an increased product temperature in the “hot product” pipe(as it exits the heat exchanger), assuming the use of saturated steam (i.e. steam at its boiling/condensingtemperature) as the heating fluid:

Steam supply

Hot product

Condensate return(back to boiler)

Valve A Valve B

Valve C

Valve D

Cold feed

Identify the validity of each possible action in this list by cheking boxes in the table – whether theaction will result in an increased product temperature or whether it will not. Assume all valves are throttling(neither fully open nor fully closed, but each one working to restrict flow through it), and that the words“open” and “close” refer to incremental motion rather than extreme travel (i.e. opening or closing each valvejust a bit, rather than fully opening or fully closing each valve):

Action Will work Will not workOpen valve AClose valve AOpen valve BClose valve B

Increase steam pressureDecrease steam pressure

Increase “cold” feed temperatureOpen valve CClose valve C

file i00015

54

Question 82

Complete the following table of equivalent temperatures:

oF oR oC K59

-10560

307-99

21588

355

file i00014

55

Question 83

Explain in your own words how a filled bulb temperature sensing instrument works, and why one mightbe used instead of an electronic temperature instrument. Include a sketch of a filled bulb instrument alongwith your explanation.

Also, explain how the Ideal Gas Law relates to some filled-bulb temperature instruments and how phasechanges relate to other types of filled-bulb temperature instruments.

This is a graded question: you will be graded on accuracy and originality (no plagiarized answers!).file i00017

56

Question 84

Suppose an instrument technician connects a multimeter (set to measure millivolts DC) to the ends ofa thermocouple cable, the other end of the cable terminating in a thermocouple junction inserted into a hotprocess.

Assuming the multimeter registers 25.841 millivolts, with an ambient temperature of 53 degreesFahrenheit at the connection point where the technician is at, and type N thermocouple cable throughout,determine the process temperature in degrees Celsius. Be sure to show all your work (including all valuestaken from a thermocouple table)!

file i00016

57

Question 85

Calculate the following values involved with heating a pot of water (2.1 pound aluminum pot, 5.6 poundsof water) from 58 degrees Fahrenheit to boiling:

• Amount of heat necessary to achieve boiling temperature = BTU

• Amount of time to achieve boil (assuming 10,000 BTU/hour heat input) = minutes

• Amount of additional heat necessary to convert 2 pounds of water into steam = BTU

Be sure to show all your work!

file i00039

58

Question 86

A common equation used in physics relates the kinetic energy, velocity, and mass of a moving object:

Ek =1

2mv2

Where,Ek = Kinetic energy (foot-pounds)m = Mass (slugs)v = Velocity (feet per second)

Manipulate this equation to solve for m, and again to solve for v. Be sure to show all your work!

v =

m =

file i03519

59

Question 87

Complete the table of values for this circuit. Be sure to show all your work!

V

I

R

P

R2

R1 R2 R3 Total

R3

R1

4.7 kΩ2.7 kΩ

3.9 kΩ

3.9 kΩ2.7 kΩ4.7 kΩ

10 mA

10 mA

file i03149

60

Question 88

Calculate the load current and load voltage in this transformer circuit:

4000 turns48 VAC 13000 turnsRload

150 Ω

Iload = Vload =

file i03245

61

Question 89

What will happen to the voltage drops across each resistor in this circuit if resistor R1 fails open?

+-

A

B

C

D

R1

R2R3

• VR1 = (increase, decrease, or stay the same)



Be sure to explain your reasoning for the answers you give!

file i03142

62

Question 90

A technician is troubleshooting a faulty optically-isolated TRIAC power switching circuit. The solenoidvalve is supposed to open up and pass liquid through it whenever the pushbutton switch is pressed, but itremains shut no matter what state the switch is in:

Solenoid valve

Pipe Pipe

To 120 VACpower source

+-

Battery TP1

TP2TP3

TP4

TP5TP6

Pinout of opto-TRIAC

Switch

Leaving the switch in its normal (“unpressed”) position, the technician measures 120 volts AC betweentest points TP5 and TP6, and 9 volts DC (normal for the battery) between test points TP1 and TP3.Based on these voltage measurements, identify two possible faults (either one of which could account forthe problem and all measured values in this circuit), and also identify two circuit elements that could notpossibly be to blame (i.e. two things that you know must be functioning properly, no matter what else maybe faulted). The circuit elements you identify as either possibly faulted or properly functioning can be wires,traces, and connections as well as components. Be as specific as you can in your answers, identifying boththe circuit element and the type of fault.

• Circuit elements that are possibly faulted1.2.

• Circuit elements that must be functioning properly1.2.

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63

Question 91

Lab Exercise

Your team’s task is to set up a temperature measurement loop using an electronic thermocouple andand an RTD. Ambient air temperature is the suggested process variable to measure. Other temperaturevariables are open for consideration, though. Each instrument in the loop should be labeled with a propertag name (e.g. “TT-37” for a temperature transmitter), with all instruments in each loop sharing the sameloop number. Write on pieces of masking tape to make simple labels for all the instruments and signal lines.

Each student must configure a “smart” transmitter for thermocouple (T/C) input, and again for RTDinput, demonstrating how to calibrate it for both sensor types. The indicator (or indicating controller) mustregister in the proper engineering units (e.g. a temperature transmitter calibrated to a range of 50 to 90degrees F should actually register 50 to 90 degrees F back at the control room display). Each team membershould choose their own (unique) temperature calibration range.

Additionally, each team member must simulate a thermocouple at some specified temperature toa thermocouple transmitter by sourcing a precise amount of millivoltage to the input terminals of thetransmitter (configured for thermocouple input). This will require consulting a thermocouple table to findthe voltage produced by a thermocouple junction at that temperature, and also the equivalent referencejunction voltage at ambient temperature (measured by a thermometer), calculating the necessary voltage toinput to the transmitter’s terminals. The purpose of this exercise is to learn how to simulate thermocouplesignals without the benefit of a self-compensating thermocouple “calibrator” device – just a precision low-voltage supply.

Each student must diagnose a fault in the system within a 5-minute time limit, correctly identifying boththe general location and nature of the fault, and logically justifying all diagnostic steps taken. Additionaltime will be given to precisely locate and rectify the fault following successful diagnosis within the allottedtime. Failure to identify both the general location and nature of the fault within the allotted time, and/orfailing to demonstrate rational diagnostic procedure will disqualify the effort, in which case the student mustre-try with a different fault. Multiple re-tries are permitted with no reduction in grade.

Objective completion table:

Performance objective Grading 1 2 3 4 TeamComponent selection and testing mastery – – – –

Loop diagram and inspection mastery – – – –Loop calibration – T/C (± 0.5% of span) mastery – – – –Loop calibration – RTD (± 0.5% of span) mastery – – – –

Millivolt simulation of T/C mastery – – – –Troubleshooting (5 minute limit) mastery – – – –

Lab question: Diagnosis proportional – – – –Lab question: Instruments proportional – – – –

Lab question: Math proportional – – – –Lab question: Tools/safety proportional – – – –

Lab questions (reviewed between instructor and student team in a private session)

• Diagnosis• Explain what will happen (and why) if a thermocouple circuit develops a short at the transmitter input

terminals (where the extension wires connect)• Explain what will happen (and why) if an RTD circuit develops a short at the transmitter input terminals

(where the lead wires connect)• Identify and explain common temperature sensor problems (thermocouple, RTD, and thermistor)• Identify what burnout mode is for a thermocouple temperature transmitter, and why it is necessary

64

• Explain why it is a bad idea to operate a portable radio transmitter (“walkie-talkie”) near an unshieldedthermocouple or RTD circuit

• Explain what will happen (and why) if the 250 ohm resistor fails open in the transmitter circuit• Explain what will happen (and why) if the 250 ohm resistor fails shorted in the transmitter circuit• Explain what will happen (and why) if the transmitter cable fails open• Explain what will happen (and why) if the transmitter cable fails shorted• Explain what will happen (and why) if loop power supply voltage is too low• Identify what things may be determined about a malfunctioning measurement loop from a single

measurement of the 4-20 mA process variable signal (e.g. suppose the indicator fails to accuratelyregister the temperature applied to a transmitter – how could a loop current measurement help you inyour diagnosis?)

• Explain what will happen (and why) in a temperature level control loop if the thermocouple wires tothe transmitter are disconnected. Assume the controller is in automatic mode when this happens, andthat the transmitter is configured for upscale burnout.

• Explain what will happen (and why) in a temperature level control loop if the thermocouple wires tothe transmitter are disconnected. Assume the controller is in automatic mode when this happens, andthat the transmitter is configured for downscale burnout.

• Instruments• Identify color codes and wire metals for a type J thermocouple• Identify color codes and wire metals for a type K thermocouple• Identify color codes and wire metals for a type T thermocouple• Identify color codes and wire metals for a type S thermocouple• Identify color codes and wire metals for a type E thermocouple• Rank types J, K, T, S, and E thermocouples according to their maximum temperatures• Explain what cold-junction (or reference junction) compensation is and why it is necessary• Explain what a thermowell is and its purpose in an industrial temperature measurement application• Explain how to distinguish thermocouple-grade wire from extension-grade wire• Explain the operations and purposes of 2-wire, 3-wire, and 4-wire RTD circuits

• Math (no calculator allowed!)• Calculate the correct loop current value (mA) given a temperature transmitter calibration range and

an applied temperature• Calculate the temperature applied to a transmitter given a calibration range and the measured loop

current value• Calculate the percentage of span error for a transmitter given a calibration range and an As-Found

calibration table• Calculate the allowable temperature error for a transmitter given an allowable percentage of span error

and a calibration range• Convert between different temperature units, without relying on the use of a reference for conversion

formulae (i.e. you must commit the formulae to memory)

65

• Tools/Safety• Explain how you can use water as a temperature calibration standard• Explain how a handheld temperature calibrator (such as the Fluke model 744) simulates a thermocouple:

exactly what type of signal does it output to the instrument under test?• Explain how a handheld temperature calibrator (such as the Fluke model 744) simulates an RTD: exactly

what type of signal does it output to the instrument under test?• Identify how to connect a handheld temperature calibrator (such as the Fluke model 744) to a

temperature transmitter to simulate a 3-wire RTD• Identify how to connect a handheld temperature calibrator (such as the Fluke model 744) to a

temperature transmitter to simulate a 4-wire RTD• Identify and explain what a dry block temperature calibrator is• Demonstrate how to shut off and tag out electrical power to your loop instruments• Identify where the danger tags are kept (for tagging out devices)• Explain how to safely check the calibration of an RTD transmitter in a temperature control loop without

causing the controller to over-react to the resistance values you apply to the transmitter as part of yourcalibration check.

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66

Question

92

Loop

dia

gra

mte

mpla

te

Description Manufacturer Model Notes

Loop Diagram: Revised by: Date:

Tag # Input range Output range

67

Loop diagram requirements

• Instrument “bubbles”• Proper symbols and designations used for all instruments.• All instrument “bubbles” properly labeled (letter codes and loop numbers).• All instrument “bubbles” marked with the proper lines (solid line, dashed line, single line, double lines,

no lines).• Optional: Calibration ranges and action arrows written next to each bubble.

• Text descriptions• Each instrument documented below (tag number, description, etc.).• Calibration (input and output ranges) given for each instrument, as applicable.

• Connection points• All terminals and tube junctions properly labeled.• All terminal blocks properly labeled.• All junction (“field”) boxes shown as distinct sections of the loop diagram, and properly labeled.• All control panels shown as distinct sections of the loop diagram, and properly labeled.• All wire colors shown next to each terminal.• All terminals on instruments labeled as they appear on the instrument (so that anyone reading the

diagram will know which instrument terminal each wire goes to).

• Cables and tubes• Single-pair cables or pneumatic tubes going to individual instruments should be labeled with the field

instrument tag number (e.g. “TT-8” or “TY-12”)• Multi-pair cables or pneumatic tube bundles going between junction boxes and/or panels need to have

unique numbers (e.g. “Cable 10”) as well as numbers for each pair (e.g. “Pair 1,” “Pair 2,” etc.).

• Energy sources• All power source intensities labeled (e.g. “24 VDC,” “120 VAC,” “20 PSI”)• All shutoff points labeled (e.g. “Breaker #5,” “Valve #7”)

68

Sam

ple

Loop

Dia

gra

m(u

sing

asin

gle

-loop

contro

ller)

Process areaField panel Control room panel

Controller

Resistor

I/P transducer

Control valve

I/P

ES 120 VAC

AS 20 PSI

Loop Diagram: Furnace temperature control

TT205

JB-12

TB-15

TB-15

3

4

1

2

Temperature transmitterTT-205 Rosemount 444

TE205

CP-1

TB-11

TB-11

1

2

7

Vishay 250 ΩTY-205a

TIC-205 Siemens PAC 353

TY-205b

TV-205 Fisher Easy-E 3-15 PSI

Fisher

H

N

3

4

22

21

19

18

TY205b

TY

205a

Breaker #4Panel L2

5

6Cable TY-205b

Cable TT-205 Cable TT-205

Cable TY-205b

TIC205

Revised by: Mason Neilan

TV205

Tube TV-205

Column #8Valve #15

546

0-1500oF 0-1500oF

Fail-closed

Reverse-acting control

TE-205 Thermocouple Omega Type K Ungrounded tip

Red

BlkRed

Yel Red

Blk

Red

Blk

Red

Blk

Wht/Blu

Blu Blu

Wht/Blu

Cable 3, Pr 1

Cable 3, Pr 2

Wht/Org

Org Org

Wht/Org

Blk

Red

Blk

Red

Blk

Wht

Red

Blk

Red

Blk

Upscale burnout


Date:


0-1500o F 4-20 mA

4-20 mA 3-15 PSI

0-100%

1-5 V 0-1500o F

April 1, 2007

69

Sam

ple

Loop

Dia

gra

m(u

sing

DC

Scontro

ller)

Field process area



DCS cabinet

Red

Blk

Red

Blk

Red

Blk

Fisher

Fisher


Blue team pressure loop April 1, 2009

Card 4

Card 6Channel 6

Channel 611

12

29

30

Red

Blk

TB-80

TB-80

Field panel JB-25

TB-52

TB-52

PT-6 Pressure transmitter Rosemount 3051CD 0-50 PSI 4-20 mA

PIC6

PT6

Cable 4, Pr 1

Cable 4, Pr 8

1

2

15

16

Cable PT-6

Red

Blk

Red

Blk

Red

Blk

Red

Blk

Red

Blk

Red

Blk

Red

Blk

Red

Blk

Cable PV-6

11

12

11

12PY6

AS 20 PSI

PV6

0-50 PSI

I/P

0-50 PSI

846

Emerson DeltaV 4-20 mA 4-20 mA HART-enabled inputPIC-6

PY-6

PV-6

I/P transducer

Controller

Control valve Vee-ball

4-20 mA 3-15 PSI

3-15 PSI 0-100% Fail-open

Duncan D.V.

Tube PV-6

Cable PT-6

Cable PV-6

Analog input

Analogoutput

Direct-acting control

H

L

70

Sam

ple

Loop

Dia

gra

m(u

sing

pneum

atic

contro

ller)




LT24

In

H

LOut

C

D

A.S. 21 PSI

Tube LT-24a Tube LT-24b

A.S. 21 PSI

Process areaBulkhead panel

14

B-104Control panel CP-11

Tube LV-24

LV24

Tube LV-24

Supply

LIC

24

Tube LV-24

(vent)

Sludge tank level control I. Leaky April 1, 2008

LT-24 Level transmitter Foxboro 13A 25-150 "H2O 3-15 PSI

3-15 PSI 3-15 PSIFoxboroLIC-24 130

LV-24 Fisher Easy-E / 667 3-15 PSI 0-100% Fail closedControl valve

Controller

file

i00654

71

Question 93

Connect a loop-powered temperature transmitter (4-20 mA output) to a DC voltage source and a metersuch that the meter will indicate a increasing signal when the temperature-sensing element is heated. Allelectrical connections must be made using a terminal strip (no twisted wires, crimp splices, wire nuts, springclips, or “alligator” clips permitted).

This exercise tests your ability to properly connect power to a loop-powered temperature transmitter,connect multiple batteries together to achieve the required total supply voltage, identify different types ofthermocouples and RTDs, properly connect either a thermocouple or an RTD to the transmitter, conditionthe electrical signal (if necessary) so the meter can properly register it, properly connect an analog meterinto the circuit, and use a terminal strip to organize all electrical connections.

- +

+ -

Meter

transmitter

Terminal strip

Resistor+ -

Batteries

TemperatureThermocouple or RTD

The following components and materials will be available to you during the exam: assorted 2-wire4-20 mA temperature transmitters calibrated to ranges inclusive of room temperature ; an assortmentof thermocouples and RTDs ; terminal strips ; lengths of hook-up wire ; 250 Ω (or approximate)resistors ; analog meters ; battery clips (holders).

You will be expected to supply your own screwdrivers and multimeter for assembling and testing thecircuit at your desk. The instructor will supply the battery(ies) to power your circuit when you are readyto see if it works. Until that time, your circuit will remain unpowered.

Meter options (instructor chooses): Voltmeter (1-5 VDC) Ammeter (4-20 mA)

Sensor type (instructor chooses): Thermocouple RTD

Study reference: the “Analog Electronic Instrumentation” chapter of Lessons In IndustrialInstrumentation, particularly the sections on loop-powered transmitters and current loop troubleshooting.Also, the “Continuous Temperature Measurement” chapter of the same textbook, particularly the sectionson thermocouples and RTDs.

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Answers

Answer 1

Answer 2

Answer 3

Differences in elevation between the sensing bulb and the indicating element only affect some classes offilled-bulb systems, not all. For these systems, the elevation will create a zero shift.

Answer 4

Answer 5

Answer 6

Answer 7

Answer 8

I’ll let you figure this one out. Be sure to show how each and every algebra step takes place!

Answer 9

• 300o C = 572o F

• 50o F = 10o C

• 4o C = 39.2o F

• 894o F = 478.89o C

• -250o F = -156.67o C

• -312o F = -191.11o C

• -150o C = -238o F

• -230o C = -382o F

• 2600o F = 1426.67o C

• 3000o C = 5432o F

Answer 10

If the student can remember the freezing and/or boiling points of water in both degrees F and degreesC, it is a trivial matter to test the formula for correctness!

Answer 11

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Answer 12

Solid: A phase of matter where both volume and shape are self-sustained.

Liquid: A phase of matter where volume, but not shape, is self-sustained.

Gas: A phase of matter where neither volume nor shape is self-sustained. Sometimes referred to asvapor, although there is a technical difference between the two words.

Plasma: An ionized gas, usually the result of very high temperature, where the constituent atoms havehad their electrons “stripped” away.

A phase change, of course, is when a substance transitions from one of these phases to another.

Follow-up question: how may a material be forced to change phase?

Answer 13

I’m not going to give away the answer here, but think about what would happen if the connecting tubingwere the same inside diameter as the bulb itself. Would this not act like one, long bulb? Think about theproblems this arrangement would cause.

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Answer 14

Bellows

ScalePointer

Liquid

Liquid

Bulb

Pivot

Bellows

Bulb

Pivot

Gas

Gas

ScalePointer

Class I or Class V Class III

Bellows

ScalePointer

Bulb

Pivot

Bellows

Bulb

Pivot ScalePointer

Vapor

Vapor

Vapor

Volatileliquid

Volatileliquid

Volatileliquid

Class IIA Class IIB

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Bellows

ScalePointer

Bulb

Pivot

Bellows

Bulb

Pivot ScalePointer

Vapor

Gas

Volatile liquid

Nonvolatileliquid

Nonvolatileliquid

Adsorptivesolid

Class IV Class IID

Follow-up question: note that a Class IIC system is not shown. Explain why.

Answer 15

This is an automatic cooling system with high and low temperature alarms.

Answer 16

Answer 17

Answer 18

Answer 19

Answer 20

Answer 21

Answer 22

Answer to challenge question: the light bulb would have to be 205 watts (two 100-watt bulbs operatingtogether would come close!).

Answer 23

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Answer 24

Partial answer:

Heat required to warm water from ambient to 100 oF = 232,400 BTU

Cost of initially heating the hot tub with electricity = $5.79

The cost of initially heating the hot tub with propane gas is very nearly the same as with electricity!

Answer 25

Answer 26

Final answer:

Total Heat Lost = 2150.48 BTU

Answer 27

• 350 K = 76.85o C

• 575o F = 1034.67o R

• -210o C = 63.15 K

• 900o R = 440.33o F

• -366o F = 93.67o R

• 100 K = -173.15o C

• 2888o C = 3161.15 K

• 4502o R = 4042.33o F

• 1000 K = 1800o R

• 3000o R = 1666.67 K

Answer 28

• 235o C = 914.67o R

• 567.2o F = 570.48 K

• 0.004 K = -459.663o F

• 830o R = 187.96o C

• -200o C = 131.67o R

• -98.25o F = 200.79 K

• 992.8o C = 1819.04o F

• -105.3o C = -157.54o F

• 1040 K = 1872o R

• 5222.6o R = 2628.29o C

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Answer 29

PV = nR(T + 273.15) Temperature in degrees C

PV = nR

(

5

9(T − 32) + 273.15

)

Temperature in degrees F

Challenge question: how is it possible to look at the original Ideal Gas Law equation and just know thetemperature must be in absolute units (the number of degrees above absolute zero) rather than degrees Cor F?

Answer 30dQdt

= Rate of heat flow (Watts)e = Emissivity factor (unitless)A = Area of radiating surface (square meters)T = Absolute temperature (Kelvin)

Challenge question: a more complete expression of the Stefan-Boltzmann equation takes into accountthe temperature of the warm object’s surroundings:

dQ

dt= eσA(T 4

1− T 4

2)

Where,T1 = Temperature of the objectT2 = Ambient temperature

Explain why this second T term is necessary for the equation to make sense.

Answer 31

V ≈ V0(1 + 3α∆T )

Answer 32

In both cases (piston moving in, and pump pulling liquid out) there will be an initial change in pressure.However, the pressure will stabilize at the exact same quantity it was at before once equilibrium is re-established. Saturated vapor pressure does not depend on the quantity of liquid or vapor, or the volume ofthe enclosed space!

Answer 33

I’ll tell you one factor that will not alter the saturated vapor pressure: liquid propane level. This meansyou can drain some propane from the tank or add some propane to it, and the pressure will not change.

Answer 34

In order of most heat required to least heat required:

• To boil a pound of water completely into steam (warming it from 211o F to 213o F).• To melt a pound of ice completely into water (warming it from 31o F to 33o F).• To heat a pound of water from 60o F to 65o F.

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Answer 35

What the technician needs is an ice-water mixture in order to guarantee stability at the freezingtemperature.

Answer 36

P at room temperature = 31.5 inches W.C.

Answer 37

k = 0.00536

T = 365.9 K at P = 1.96 bar

Answer 38

Pideal = 5.38 PSIG

The pressure gauge will never quite reach 5.38 PSIG because not all the air in this closed system hasbeen heated to the boiling temperature of water (373.15 K)!

Answer 39

Answer 40

Answer 41

Answer 42

Partial answer:

RT = 1470.4 Ω at 120o C

Answer 43

Answer 44

Answer 45

Partial answer:

RTD

3-wire RTD

BlkBlk

Red

Answer 46

Partial answer:

• Vout = 0.000 mV at T = 0o C

• Vout = 1.578 mV at T = 35o C

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Answer 47

The following resistor values are suggested, but are not the only correct values that may be used toobtain the same calibration:

RTD1 kΩ

−

+1 V

European α

1 kΩ

1 kΩ

1 kΩ

1 kΩ 73.935 kΩ

+−

Vout

Answer 48

Partial answer:Extra resistance introduced into the RTD arm of the bridge circuit by the cable wires will definitely

cause temperature measurement errors, because it makes the RTD “appear” to have more resistance thanit really does. This will result in an upward zero shift (a falsely high temperature indication).

Answer 49

Partial answer:Vout = 0 mV

Answer 50

Answer 51

The statement means that the RTD is made of platinum wire, with a resistance of 100 Ω at a referencetemperature (Rref ) of 0o C. The temperature coefficient of resistance (α) at this reference temperature of0o C is 0.00385.

Answer 52

α = 0.00392 is an American RTD standard. α = 0.00385 is a European RTD standard (DIN 43760).

Answer 53

As temperature increases, the lamp becomes brighter.

Answer 54

I’ll let you explain the working principle of both circuits!

Answer 55

Partial answer:

• Vout = 14.08 mV at T = 200o C

Answer 56

Vout = 97.95 mV

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Answer 57

0o C 200o C

180 Ω

100 Ω100o C50o C 150o C

0o C 200o C

0 mV

7 mV

100o C50o C 150o C

The contrast is obvious. I’ll let you reach your own conclusions!

Answer 58

Here is a very terse answer:

P = I2R

Answer 59

Answer 60

Answer 61

Answer 62

Answer 63

Answer 64

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Answer 65

Answer 66

Answer 67

Partial answer:

• Tprocess = 32o F; Voltmeter voltage = 0 mV• Tprocess = 100o C; Voltmeter voltage = 4.279 mV

Answer 68

Partial answer:

• Tprocess = -165o F; Voltmeter voltage = -3.836 mV• Tprocess = 2350o F; Voltmeter voltage = 51.982 mV

Answer 69

Partial answer:

• Tmeasurement = 250o F ; Treference = 60o F ; Voltmeter voltage = 5.630 mV• Tmeasurement = -238o F ; Treference = 80o F ; Voltmeter voltage = -7.864 mV

Answer 70

• Treference = 70o F ; Voltmeter voltage = 20.018 mV ; Tmeasurement = 941o F• Treference = 65o F ; Voltmeter voltage = 5.833 mV ; Tmeasurement = 321o F• Treference = 52o F ; Voltmeter voltage = 31.420 mV ; Tmeasurement = 1410o F• Treference = 73o F ; Voltmeter voltage = -2.027 mV; Tmeasurement = -20o F

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Answer 71

Making both voltmeter wires out of metal B allows this simplification of junctions:


Voltmeter

+-


A

B

A

B

Measurementjunction

junctionReference

B

B

Getting rid of metal B completely works just as well! Now the A-C and B-C junctions act as asingle reference junction, because they are held at the same temperature by the thermal conductivity of theterminal block:


Voltmeter

+-


A

B

A

B

Measurementjunction

junctionReference

C

C

Answer 72

Yes they are, as per the Law of Intermediate metals for thermocouple circuits.

Answer 73

• Voltmeter voltage = 11.857 mV; Tprocess = 2178o F• Voltmeter voltage = 6.381 mV; Tprocess = 1310o F• Voltmeter voltage = 1.972 mV; Tprocess = 502o F• Voltmeter voltage = 0 mV; Tprocess = 32o F

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Answer 74

• Tmeasurement = 1500o F ; Treference = 65o F ; Voltmeter voltage = 61.145 mV• Tmeasurement = 212o F ; Treference = 74o F ; Voltmeter voltage = 4.925 mV• Tmeasurement = -360o F ; Treference = 32o F ; Voltmeter voltage = -9.229 mV• Tmeasurement = -132o F ; Treference = -30o F ; Voltmeter voltage = -2.876 mV

Answer 75

Hint: in order to answer this question, you are going to have to research what standard thermocoupletypes each dissimilar-metal junction forms, and the reference book(s) will tell you which metal is positiveand which is negative.

VoltmeterCu

CuCu

Process

300o F

85o F

C (Constantan)

(no voltage)

VoltmeterCu

Cu

Process

300o F

85o F

C (Constantan)

Fe

Answer 76

This circuit only has one reference junction, if you count the two terminal connections at the indicator asa single junction. The junction mid-way between the thermocouple head and the indicator is not a referencejunction because it is not a junction of dissimilar metals.

Answer 77

Here is an important hint: being located so close to the furnace wall, the thermocouple head will likelybecome very hot!

Answer 78

RTDs are more linear than thermocouples. This means that RTDs tend to be more precise within theirrated temperature ranges than thermocouples within their rated temperature ranges when interpreted by alinear transmitter circuit, all other factors being equal.

Answer 79

Answer 80

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Answer 81

This is a graded question – no answers or hints given!

Answer 82


Answer 83


Answer 84


Answer 85


Answer 86


Answer 87


Answer 88


Answer 89


Answer 90


Answer 91

Answer 92

Your loop diagram will be validated when the instructor inspects the loop with you and the rest of yourteam.

Answer 93

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