ISA Seminars on the Web Live Experts on Hot Topics

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1 ISA Seminars on the Web Live Experts on Hot Topics Standards Certification Education & Training Publishing Conferences & Exhibits Introduction to Temperature Measurement FG05W2 Version Standards Certification Education & Training Publishing Conferences & Exhibits

2 Seminar Logistics Seminar materials Downloadable presentation Question and Answer session (audio and ) Survey Earn 1.5 Professional Development Hours (PDH) Seminar length 90 minute total presentation Three approximately 20 minute instructional presentations Three approximately 10 minute question and answer sessions 3 Audio Instructions Please note the following during the seminar: As a participant, you are in a listen-only mode. You may ask questions via the internet, using your keyboard, at any time during the presentation. However, the presenter may decide to wait to answer your question until the next Q&A Session. If you have audio difficulties, press *0. 4

3 Audio Instructions for Q & A Sessions Questions may be asked via your telephone line. Press the *1 key on your telephone key-pad. If there are no other callers on the line, the operator will announce your name and affiliation to the audience and then ask for your question. If other participants are asking questions, you will be placed into a queue until you are first in line. While in the queue, you will be in a listen-only mode until the operator indicates that your phone has been activated. The operator will announce your name and affiliation and then ask for your question. 5 Introduction of the Presenter ISA Presenter Larry Thompson, CAP ISA Adjunct instructor since B.A.A.S Tarleton State University. Instructor for Texas State Technical College in Instrumentation ( ), Computer Networking and System Administration ( ), E-Commerce Technology ( ). CCST Certificate, FCC Radiotelephone License (General, formerly First Class). Served 20 years USAF primarily in Electronic Encryption Systems. Owned and managed own services business since Designed, developed, taught and maintained industrial controls in many varied applications. Author of ISA books: Industrial Data Communications and Basic Electrics/Electronics for Control 6

4 Goals of this Session Discuss the measurement principles, instrument technologies, and applications to process conditions for temperature measurement 7 Section 1: Intro-Temperature Measurement Principles Classification of Thermometers Temperature Scales Liquid Filled Systems Vapor Filled Systems Bimetallic elements 8

5 Room Heating Example Room Temperature Measurement Where do you mount thermostat? What kind of measuring device? What temperature are you measuring? At what temperature does it turn the furnace on? At what temperature does it turn the furnace off? What causes the room temperature to vary? What accuracy is required of this measurement? Is reliability a concern? 10

6 Temperature Measurement Measurement of heat energy of a substance May be measured by contact May be measured by radiation Is a key process measurement Characteristics of material change through temperature Density changes through temperature change Three states of matter are dependent upon (among other things) temperature (solid, liquid, gas) 11 Classification of Temperature Devices Classified as to absolute or temperature sensors Classified as to mechanical or electrical Classified by construction 12

7 Temperature Scales 13 Basic Liquid in Glass Thermometer 14

8 Types of Liquid in Glass Thermometers 15 Liquid Filled System Thermometer Completely filled with Mercury 16

9 Volatile Liquid Filled System Thermometer 17 Comparison of Filled Systems LIQUID-FILLED VAPOR GAS-FILLED RANGE -150 TO 1200 o F -100 TO 550 o F -100 TO 1500 o F ( to C) (-73.3 to 287 C) (-73.3 to C) ADVANTAGES Low on-off differential, fast response, small bulb size Insensitive to ambient temperature changes Insensitive to ambient temperature changes LIMITATIONS Requires ambient compensation Large bulb required, slow response Large bulb required, slow response 18

10 Bimetallic Thermometers 19 Other Bimetallic Applications On-Off Switch (coffee maker) Thermostat (continuous) Circuit Breakers (Low voltage) Motor Overloads Directional Signals Others? 20

11 Considerations Bimetallics are basically on-off No way to easily transmit a continuous signal Filled systems; while analog and have ability to transmit, are slow Liquid in Glass Thermometers are only as accurate as their insertion level All filled systems, liquid in glass thermometers, and to an extent; bimetallic devices do not have an exceptionally high range or large span, nor do they function well below a determined temperature. 21 Review of Key Points Principles Classification of Thermometers Temperature Scales Liquid Filled Systems Vapor Filled Systems Bimetallic elements 22

12 Live Question and Answer Session During Q&A, questions may be asked via your telephone line. Press the *1 key on your telephone key-pad. If there are no other callers on the line, the operator will announce your name and affiliation to the audience and then ask for your question. If other participants are asking questions, you will be placed into a queue until you are first in line. While in the queue, you will be in a listen-only mode until the operator indicates that your phone has been activated. The operator will announce your name and affiliation and then ask for your question. 23 Section 2: RTDs and Thermistors 24

13 Basic RTD RTD IN A CUTAWAY VIEW SHOWING MEASURING ELEMENT PLATINUM LEADS RESISTANCE ELEMENT 25 Basic RTD Circuit (2 Wire)

14 3 Wire Circuit 4 - Wire RTD

15 RTD Construction INSULATOR DISC PLATINUM LEADS PLATINUM ELEMENT PLATINUM WINDING BIRD CAGE RTD CERAMIC BODY PARTIALLY SUPPORTED RTD PLATINUM LEADS GLASS BODY FULLY SUPPORTED RTD PLATINUM COIL WOUND ON GLASS FORMER 29 RTD with ceramic body 30

16 Sheathed RTD METAL SHEATH LEAD WIRES FILLER (POWDER OR CEMENT) MANDREL (WITH PLATINUM ELEMENT) 31 Smart RTDs

17 RTD Considerations Very stable, can have less than 1 C drift over 5 years * Most linear of temperature sensors Does not require a cold junction reference Does require lead resistance compensation Temperatures from -200 to 650 C commonly available Industry typical is 385 or 392 Platinum, 0 C 385 refers to Ohms/Ohm/Deg C 392 refers to Ohms/Ohm/Deg C There is also a Ohms/Ohm/Deg C * Dependent upon type 33 Thermistors Designer resistor Electrical resistance of material varies greatly with temperature Limited spans, low cost High accuracy & stability Limited to low-medium temps Typically resistance decreases as temperature increases 3% to 5% per F (5% to 9% per C) Can be had with either positive or negative temperature coefficient. May be had in a variety of shapes and forms 34

18 Thermistor illustrated 35 Review of Key Points Basic RTD 2-Wire RTD 3- Wire RTD 4-Wire RTD Sheathed RTD RTD Considerations Thermistors 36

19 Live Question and Answer Session During Q&A, questions may be asked via your telephone line. Press the *1 key on your telephone key-pad. If there are no other callers on the line, the operator will announce your name and affiliation to the audience and then ask for your question. If other participants are asking questions, you will be placed into a queue until you are first in line. While in the queue, you will be in a listen-only mode until the operator indicates that your phone has been activated. The operator will announce your name and affiliation and then ask for your question. 37 Section 3: Thermocouples Basic Thermocouple Principles Thermocouple Materials Thermocouple Extension Wire Thermocouple Construction and Assemblies Thermocouple Considerations Thermocouple Loop Calibration 38

20 Basic Thermocouple T1 T2 MEASURING JUNCTION REFERENCE JUNCTION 39 Reference Junction 40

21 Modern Ice Point THERMOCOUPLE INSTRUMENT MEASURING JUNCTION REFERENCE JUNCTION 41 Standard Thermocouple Materials ISA DESIGNATION B WIRE MATERIALS Platinum 30% Rhodium/ Platinum 6% Rhodium NOMINAL TEMP. RANGE C RECOMMENDED ATMOSPHERE FEATURES 0 TO 1820 C Inert or Oxidizing Easily contaminated, (32 to 3308 F) use in non-metallic, silica-free protecting tube. E Nickel 10% Chromium/ Copper-Nickel -270 to 1000 C Vacuum, Inert, or Oxidizing (-454 to 1832 F) Highest EMF output, larger drift than other base-metal thermocouples J Iron/Copper-Nickel -210 to 760 C Vacuum, Inert, Oxidizing, (-346 to 1400 F) or Reducing May rust or become brittle in sub-zero temperatures K Nickel 10% Chromium/ Nickel 5% Aluminum and/ or Silicon -270 to 1372 C (-454 to F) Inert or Oxidizing Most linear of all thermocouples. Short life in marginally oxidzing atmospheres. 42

22 Standard Thermocouple Materials (cont d) ISA DESIGNATION R WIRE MATERIALS Platinum 13% Rhodium/ Platinum NOMINAL TEMP. RANGE C -50 to 1768 C (-58 to 3214 F) RECOMMENDED ATMOSPHERE Inert or Oxidizing FEATURES Good linearity at high temperatures, small size, fast response, easily contaminated, use in protecting tube. S Platinum 10% Rhodium/ Platinum -50 to 1768 C (-58 to F) Inert or Oxidizing Good for sub-zero use because of superior resistance to corrosion from moisture, limited temp. range. Copper/ Copper Nickel Tungsten/Tungsten- 26% Rhenium -270 to 400 C (-454 to 752 F) -18 to 2315 C (-.4 to 4199 F) Vacuum, Inert Oxidizing or Reducing Inert or Vacuum Same as Type R Good linearity at high temperatures, brittle, hard to handle. Tungsten 6% Rhenium/ Tungsten 26% Rhenium -18 to 2315 C (-.4 to 4199 F) Inert or Vacuum Good linearity at high temperatures, slightly less brittle, than above. 43 Standard Thermocouple Extension Leads 44

23 Bare Wire Thermocouple Insulation Types Typical Thermocouple Assembly

24 Thermocouple Loop Calibration 47 Thermocouple Considerations Thermocouples drift (depending on type) from 2 to 5 C in the same direction annually. Can measure the highest temperatures of any contact sensor Can measure the lowest temperatures of any contact sensor Have more errors in selection, installation, maintenance, and calibration then other sensors Are relatively linear over a portion of their range They will burn open 48

25 Review of Key Points Basic Thermocouple Principles Thermocouple Materials Thermocouple Extension Wire Thermocouple Construction and Assemblies Thermocouple Considerations Thermocouple Loop Calibration 49 How Many People Are at Your Site? Poll Slide Click on the appropriate number indicating the number of people that are at your site.

26 Live Question and Answer Session During Q&A, questions may be asked via your telephone line. Press the *1 key on your telephone key-pad. If there are no other callers on the line, the operator will announce your name and affiliation to the audience and then ask for your question. If other participants are asking questions, you will be placed into a queue until you are first in line. While in the queue, you will be in a listen-only mode until the operator indicates that your phone has been activated. The operator will announce your name and affiliation and then ask for your question. 51 Related ISA Courses FG07 Introduction to Industrial Automation and Control TC05 Tuning Control Loops TS00 CCST Review Course All ISA courses are available any time as on-site training For more information: or (919)

27 ISA Certifications Certified Automation Professionals (CAP ) Certified Control Systems Technician (CCST ) Please visit us online for more information on any of these programs, or call (919) Please take our Web Seminar Survey via Zoomerang The seminar survey was sent to you via during the seminar. Please do not forget to complete the Zoomerang survey.

28 Conclusion This is the end of: Introduction to Temperature Measurement 55