Introduction to Pressure Measurement

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Introduction to Pressure Measurement FG05W5 Version 1.

1 Introduction to Pressure Measurement FG05W5 Version Standards Certification Education & Training Publishing Conferences & Exhibits 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 2

2 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. 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. 4

3 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 5 Goals of this Session Discuss the measurement principles, instrument technologies, and applications to process conditions for pressure measurement 6

4 Course Objectives Define pressure in terms of force and mass Describe how fluid height/specific gravity affect pressure Differentiate between absolute and gage pressure Describe the operation of a manometer Describe the operation of pressure gages Describe the operation of electrical pressure transducers Identify different types of electrical pressure transducers Describe the operation of pressure transmitters Describe installation considerations for pressure instruments Describe methods of protecting pressure measurement devices from damage 7 Section 1: Intro to Pressure Measurement Introduction to Pressure: Force Exerted by Liquids Forces Exerted by Gas Pressure Measurement: Units of Measurement Converting Measurement Units Differential Pressure Specific Gravity 8

5 What is Pressure Pressure is force over an area Work is force through a distance Therefore, pressure is potential energy Area = l x w force w l 9 Liquid Force Over An Area P = F/A Atmospheric Pressure I n c P r r e e a s s s i u n r g e 0 Area = r 2 Force = Weight of liquid 10

6 Gas Pressure Over An Area A gas (other than a blanket of air atmosphere) exerts an equal force throughout its constraint (vessel). 11 Liquid Pressure 12

7 Common Conversions 13 Atmospheric Pressure

8 Differential Pressure (1) All pressure measurement is differential Gauge is measured as difference between measured and atmospheric Absolute is measured as difference between measured and absolute (complete vacuum) In measurement when it is called differential, it means the difference between two pressures of which neither may be absolute or atmospheric. Differential simply means difference between 15 Differential Pressure (2) 30 psi 30 psi High Side Low Side Hi Lo Hi Lo 30 psi 0 psi 30 psi 0 psi Positive Pressure Negative Pressure 16

Differential Pressure (3) 17 Specific Gravity Ratio of density of a process material to the density of water or air Specific gravity of water = 1 Specific gravity of air = 1

9 Differential Pressure (3) 17 Specific Gravity Ratio of density of a process material to the density of water or air Specific gravity of water = 1 Specific gravity of air = 1 Example: Density Mercury = lbs/ft3 Specific Gravity = lbs/62.4 lbs = 13.6 Density (petroleum) = 54.8 lbs./cu. ft. Specific Gravity = 54.8 lbs/62.4 lbs =

10 Review of Key Points Introduction to Pressure: Force Exerted by Liquids Forces Exerted by Gas Pressure Measurement: Units of Measurement Converting Measurement Units Differential Pressure Specific Gravity 19 Section 2: Physical Measurement Manometers: Basic Manometers Types of Manometers Mechanical Pressure Transducers: Principles of Mechanical Pressure Transducers Types of Pressure Transducers Pneumatic Pressure Transmitters 20

11 U-Tube Manometers U-Tube Manometers (cont d)

12 Hydrostatic Head Pressure 23 Well Manometers

13 Example of Pascal s Law Bourdon, Helical, Spiral, Elements 26

14 Bellows 27 Diaphragm Diaphragm: front side capsule 28

15 Flapper and Nozzle Pneumatic Transmitters

16 Review of Key Points Manometers: Basic Manometers Types of Manometers Mechanical Pressure Transducers: Principles of Mechanical Pressure Transducers Types of Pressure Transducers 31 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. 32

17 Section 3: Electrical Pressure Measurement Electrical Pressure Elements: Principles of Electrical Pressure Transducers Types of Electrical Pressure Transducers Electronic Pressure Elements: Strain Gage Crystals Electronic Pressure Transmitters Installation Considerations 33 Electronic Pressure Element Principles 34

18 Capacitive Pressure Sensor - lead wires - capacitor plates - sensing plate - solid insulation - silicon oil - isolating diaphragm - welded seals 35 Current to Pneumatic (I/P) Transducer Used to convert current signal to pressure signal

19 Strain Gauge 37 Load Cell 38

20 Piezoelectric Forces 39 Crystal Pressure Sensor 40

21 Typical dp Electronic Transmitter 41 Digital Pressure Transmitter Real Engineering Language Tag = PIT-010 Value = Units = Psig Device status = Good/bad Sensor status = Good/bad PV value = Good/bad HI/HI alarm HI alarm LO alarm LO/LO alarm Trending Foundation Fieldbus Transmitter 42

22 Pressure Transmitter Installation 43 Pig Tail 44

23 Zero Suppression 45 Key Points Electrical Pressure Elements: Principles of Electrical Pressure Transducers Types of Electrical Pressure Transducers Electronic Pressure Elements: Strain Gage Crystals Electronic Pressure Transmitters Installation Considerations 46

24 How Many People Are at Your Site? Poll Slide Click on the appropriate number indicating the number of people that are at your site. 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. 48

25 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) 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)

26 Conclusion This is the end of: Introduction to Pressure Measurement 51

Pressure Measurement

Pressure Measurement Manometers Sensors, Transducers Ashish J. Modi Lecturer, Dept. of Mech.Engg., Shri S.V.M. inst. Of Technology, Bharuch Pressure Pressure is a force per unit area exerted by a fluid