8/18/2019 Chap7- Engineering Measurements
1/12
4/2/20
ChapterChapter 77
Engineering MeasurementsEngineering Measurements
PREP004 – Introduction to Applied Engineering
College of Engineering - University of Hail
Fall 2009
Examples of MeasurementsExamples of Measurements
♦♦CheckCheck youryour weightweight
♦♦Read your watchRead your watch
♦♦Take your temperatureTake your temperature
♦♦Read the speed indicator of your carRead the speed indicator of your car
What kinds of measurements did you makeWhat kinds of measurements did you make
today ?today ?
8/18/2019 Chap7- Engineering Measurements
2/12
4/2/20
Standards of MeasurementStandards of Measurement
,,
tool to compare some dimension of antool to compare some dimension of an
object to a standard.object to a standard.
Who needs good measurements?Who needs good measurements?
Engineers in IndustryEngineers in Industry
Doctors
Scientists
You and me (Every body)You and me (Every body)
Regulators (trade)
8/18/2019 Chap7- Engineering Measurements
3/12
4/2/20
Measurements for industry and tradeMeasurements for industry and trade
Design and develop newDesign and develop newproductsproducts
Manufacture of roducts thatManufacture of roducts thatmeet specificationsmeet specifications
Ensure compatibility andEnsure compatibility andinteroperability of productsinteroperability of products
Improve production processesImprove production processes
ReduceReduce scrapscrap
Improve Product QualityImprove Product Quality
nsure a r an equ a e ra e
80% of traded goods are based on
standards and regulations whereconformity assessment and hence
measurements are highly required.
Accurate, consistent measurement enables fairtrade.
WhyWhy measurements and metrologymeasurements and metrology
are importantare important??
It guarantees manufacturing quality andsupports innovation.
It makes an annual contribution of Billions ofDollars to wealth creation .
It underpins our safety, our health and ourualit of life.
It facilitates environmental management. It provides for effective regulations and Laws.
6
8/18/2019 Chap7- Engineering Measurements
4/12
4/2/20
Wrong measurements can beWrong measurements can be disastrousdisastrous
Measurement ErrorsMeasurement Errors
“Mission specifications called for“Mission specifications called forusingusing metric unitsmetric units, but the, but theLockheed group sent navigationLockheed group sent navigationinformation ininformation in BritishBritish unitsunits. The. Themixmix--up meant that Lockheedup meant that Lockheedengineers modelled navigationengineers modelled navigationwith pounds force (the Englishwith pounds force (the Englishunit for measuringunit for measuring thrusterthrusterimpulse) while JPL did itsimpulse) while JPL did itscalculations incalculations in newtonsnewtons (the(themetric measurement). One poundmetric measurement). One poundforce is equivalent toforce is equivalent to 44..4545newtonsnewtons.”.”
(Report on the loss of NASA’s Mars Orbiter spacecraft)
Systems of MeasurementsSystems of Measurements
British System of Measurements (BS)
Old system based on the inch (length)
The International System of
Units (SI) is the modern form of
and still in use in some industries
(petrochemicals) generally a system devised
around the convenience of the
number 10.
It is the world's most widely used
system of measurement, both in
industry, science and commerce.
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٨
8/18/2019 Chap7- Engineering Measurements
5/12
4/2/20
International System (SI)International System (SI)
Seven Basic Units of MeasurementsSeven Basic Units of Measurements
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٩
SI Derived UnitsSI Derived Units
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH
8/18/2019 Chap7- Engineering Measurements
6/12
4/2/20
StandardStandard prefixesprefixes has been defined in orderhas been defined in order toto
measure very large and very small quanti tiesmeasure very large and very small quanti ties
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH
Examples of use of PrefixesExamples of use of Prefixes
•• ExampleExample 11:: 1010--66 kg =kg = 11 mg (one milligram),mg (one milligram),
but notbut not 1010--66 kg =kg = 11 µkg (oneµkg (one microkilogrammicrokilogram))
•• ExampleExample 22:: Consider the example of the heightConsider the example of the height
of the Washin ton Monument. We ma write:of the Washin ton Monument. We ma write:
hhWW == 169 000169 000 mm =mm = 16 90016 900 cmcm
== 169169 m =m = 00..169169 kmkm
8/18/2019 Chap7- Engineering Measurements
7/12
4/2/20
Other Units of MeasurementsOther Units of Measurements
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٣
What Engineers measureWhat Engineers measure
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
,of a turbine etc..)
8/18/2019 Chap7- Engineering Measurements
8/12
4/2/20
Why Engineers measure ?Why Engineers measure ?
To describe the current state of the process.
To state requirements quantitatively and
demonstrate compliance.
To track process and predict progress of
.
To analyze costs and benefits.
How do we measure ?How do we measure ?
•• UsingUsing measurementmeasurement
instrumentsinstruments (such as a caliper(such as a caliper
to measure the length of a workto measure the length of a work
piece or the voltmeter to measurepiece or the voltmeter to measure
the voltage of electrical currentthe voltage of electrical current
for example)for example)
•• Using aUsing a measurement system.measurement system.
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٦
8/18/2019 Chap7- Engineering Measurements
9/12
4/2/20
Result of a MeasurementResult of a Measurement
XX : Measured Value: Measured Value
TT : True Value: True Value
EE : Error of Measurement: Error of Measurement
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٧
Systematic Errors : Deal with them
by calibration of the measuring
instrument
Random Errors : Deal with
them by repeating themeasurements many times
and determine statistically
these errors.
Accuracy and Precision in Measurements Accuracy and Precision in Measurements Accuracy refers to how closely the measured value of a quantity corresponds to its
“true” value.
measurement accurac : closeness of a reement between a measured uantit
value and a true quantity value of the measurand.
Precision expresses the degree of reproducibility, or agreement between repeated
measurements.
Accuracy is tel ling the tru th and Precision is tell ing the same sto ry again and again.
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٨
High Accuracy
High Precision
Low Accuracy
High Precision
Low Accuracy
Low Precision
8/18/2019 Chap7- Engineering Measurements
10/12
4/2/20
International and National Organizations forInternational and National Organizations for
Standards and MetrologyStandards and Metrology
e n erna ona rgan za on or
Standardization (ISO)
The International Office of Legal
Metrology (OIML)
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٩
Mesures
Saudi Arabian Organization for
Standardization and Quality (SASOQ)
Home WorkHome Work 44--11
use touse to measure the following:measure the following:
A A.. TemperatureTemperature ____________________ ____________________
BB.. VolumeVolume ____________________ ____________________
CC. Length. Length ___________________ ___________________
D.D. TimeTime ____________________ ____________________
E.E. WeightWeight ____________________ ____________________
F.F. Pressure ____________________ Pressure ____________________
8/18/2019 Chap7- Engineering Measurements
11/12
4/2/20
Home WorkHome Work 44--22
following conversions :following conversions :
A A.. T=T= 6565 C = ……. F = ………. K = ……C = ……. F = ………. K = ……
BB.. V =V = 1010 Gallons = …… l = ……. mGallons = …… l = ……. m33
CC. L =. L = 15401540 miles = …… km = …….. m = …. inchmiles = …… km = …….. m = …. inch
D.D. T =T = 1515 h = ……… min = ……… s = ….. dayh = ……… min = ……… s = ….. day
E.E. use any measurement results and make theuse any measurement results and make the
necessary conversions.necessary conversions.
Research QuestionResearch Question 44--33
What is aWhat is a vernier vernier calipercaliper and how does itand how does it
work?work?
Give some engineering situations where thisGive some engineering situations where this
instrument is used .instrument is used .
State some illustrations and examples.State some illustrations and examples.
8/18/2019 Chap7- Engineering Measurements
12/12
4/2/20
Additional Readings Additional Readings
http://en.wikipedia.org/wiki/International_System_of_Unitshttp://en.wikipedia.org/wiki/International_System_of_Units
http://hctmetrology.tripod.comhttp://hctmetrology.tripod.com (Arabic web on dimensional metrology)(Arabic web on dimensional metrology)
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٢٣
Thank ouThank ou
Any Questions ? Any Questions ?
PREPPREP004004 – – Introduction to Applied Engineering , College of Engineering,Introduction to Applied Engineering , College of Engineering, UoHUoH ٢٤
Recommended