1. Chapter 7 Engineering Measurements PREP004 – Introduction to Applied Engineering College of Engineering - University of Hail Fall 2009

2. Examples of Measurements Examples of Measurements You are making a measurement when you  Check your weight  Read your watch  Take your temperature  Read the speed indicator of your car What kinds of measurements did you make today ?

3. Standards of Measurement When we measure, we use a measuring tool to compare some dimension of an object to a standard.

4. Who needs good measurements?  Engineers in Industry You and me (Every body)  You and me (Every body)  Regulators (trade)  Doctors  Scientists

5. Measurements for industry and trade  Design and develop new products  Manufacture of products that meet specifications  Ensure compatibility and interoperability of products  Improve production processes  Reduce scrap  Improve Product Quality  Ensure fair and equitable trade  80% of traded goods are based on standards and regulations where conformity assessment and hence measurements are highly required.

6.  Accurate, consistent measurement enables fair trade.  It guarantees manufacturing quality and supports innovation.  It makes an annual contribution of Billions of Dollars to wealth creation.  It underpins our safety, our health and our quality of life.  It facilitates environmental management.  It provides for effective regulations and Laws. Why measurements and metrology are important? 6

7. Wrong measurements can be disastrous Measurement Errors “Mission specifications called for using metric units, but the Lockheed group sent navigation information in British units. The mix-up meant that Lockheed engineers modelled navigation with pounds force (the English unit for measuring thruster impulse) while JPL did its calculations in newtons (the metric measurement). One pound force is equivalent to 4.45 newtons.” (Report on the loss of NASA’s Mars Orbiter spacecraft)

8. Systems of Measurements PREP004 – Introduction to Applied Engineering, College of Engineering, UoH8 British System of Measurements (BS) Old system based on the inch (length) and still in use in some industries (petrochemicals) The International System of Units (SI) is the modern form of the metric system and is generally a system devised around the convenience of the number 10.metric system It is the world's most widely used system of measurement, both in industry, science and commerce. system of measurement

9. International System (SI) Seven Basic Units of Measurements PREP004 – Introduction to Applied Engineering, College of Engineering, UoH9

10. SI Derived Units PREP004 – Introduction to Applied Engineering, College of Engineering, UoH 10

11. Standard prefixes has been defined in order to measure very large and very small quantities PREP004 – Introduction to Applied Engineering, College of Engineering, UoH 11

12. Examples of use of Prefixes Example 1: 10 -6 kg = 1 mg (one milligram), Example 1: 10 -6 kg = 1 mg (one milligram), but not 10 -6 kg = 1 µkg (one microkilogram) but not 10 -6 kg = 1 µkg (one microkilogram) Example 2: Consider the example of the height of the Washington Monument. We may write: Example 2: Consider the example of the height of the Washington Monument. We may write: h W = 169 000 mm = 16 900 cm h W = 169 000 mm = 16 900 cm = 169 m = 0.169 km = 169 m = 0.169 km

13. Other Units of Measurements PREP004 – Introduction to Applied Engineering, College of Engineering, UoH13

14. What Engineers measure 14 Engineering is a process that results in useful products. During his work, the engineer measures products specifications (length, height, depth, weight, etc..) and process characteristics (Temperature and pressure of fluid flows, speed of a turbine etc..)

15. Why Engineers measure ? 15 To describe the current state of the process. To state requirements quantitatively and demonstrate compliance. To track process and predict progress of engineering project. To analyze costs and benefits.

16. How do we measure ? Using measurement instruments (such as a caliper to measure the length of a work piece or the voltmeter to measure the voltage of electrical current for example) Using measurement instruments (such as a caliper to measure the length of a work piece or the voltmeter to measure the voltage of electrical current for example) Using a measurement system. Using a measurement system. PREP004 – Introduction to Applied Engineering, College of Engineering, UoH16

17. Result of a Measurement X : Measured Value T : True Value E : Error of Measurement PREP004 – Introduction to Applied Engineering, College of Engineering, UoH17 Systematic Errors : Deal with them by calibration of the measuring instrument Random Errors : Deal with them by repeating the measurements many times and determine statistically these errors.

18. Accuracy and Precision in Measurements PREP004 – Introduction to Applied Engineering, College of Engineering, UoH18 Accuracy refers to how closely the measured value of a quantity corresponds to its “true” value. measurement accuracy : closeness of agreement between a measured quantity value and a true quantity value of the measurand. Precision expresses the degree of reproducibility, or agreement between repeated measurements. Accuracy is telling the truth and Precision is telling the same story again and again. High Accuracy High Precision Low Accuracy High Precision Low Accuracy Low Precision

19. International and National Organizations for Standards and Metrology PREP004 – Introduction to Applied Engineering, College of Engineering, UoH19 The International Organization for Standardization (ISO) The International Office of Legal Metrology (OIML) Bureau International des Poids et des Mesures Saudi Arabian Organization for Standardization and Quality (SASOQ)

20. Home Work 4-1 S tate the tool (s) and the Units you would use to measure the following: A. Temperature____________________ B. Volume ____________________ C. Length____________________ D. Time____________________ E. Weight____________________ F. Pressure ____________________ F. Pressure ____________________

21. Home Work 4-2 Use any online converter to make the following conversions : A. T= 65 C = ……. F = ………. K = …… B. V = 10 Gallons = …… l = ……. m3 C. L = 1540 miles = …… km = …….. m = …. inch D. T = 15 h = ……… min = ……… s = ….. day E. use any measurement results and make the necessary conversions.

22. Research Question 4-3 What is a vernier caliper and how does it work? Give some engineering situations where this instrument is used. State some illustrations and examples.

23. Additional Readings  http://en.wikipedia.org/wiki/International_System_of_Units http://en.wikipedia.org/wiki/International_System_of_Units  http://hctmetrology.tripod.com (Arabic web on dimensional metrology) http://hctmetrology.tripod.com PREP004 – Introduction to Applied Engineering, College of Engineering, UoH23

24. PREP004 – Introduction to Applied Engineering, College of Engineering, UoH24 Thank you Any Questions ?