This document provides an introduction to instrumentation and measurement. It discusses key parameters that are continuously monitored in process plants like pressure, flow, temperature, and level. It defines instrumentation as the division of engineering that deals with measuring techniques, devices, and associated problems. The document outlines different types of instruments used to measure pressure, flow, temperature, and level. It also discusses concepts like transducers, calibration, accuracy, precision, range, and errors in instrumentation.

1. B. KARTHIK ANAND
Asst. Professor
Dept. of Mechanical Engineering
V.B.I.T

6. Introduction to Instrumentation
• Instrumentation is all about measurement and control.
Any process plant has to continuously monitor and
control four important parameters.
• Pressure
• Flow
• Temperature
• Level
This can only be done with the help of instrumentation.
To monitor continuously, first these parameters are to be
measured and then controlled.

7. Instrument
• The Human senses cant provide exact
quantitative information about the
knowledge of events occurring in our
environments.
• Therefore for this reason accurate and
precise measurements came into
existence called as Instruments.

8. Instrumentation
• The division of engineering science which
deals with measuring techniques ,
devices and their associated problems is
called as Instrumentation.
• Application…..

9. Measure

10. Measurement
• The word measurement is used to tell us about the length,
the weight ,the temperature, the colour or change in one of
these physical entities of a material.
• This also provides us with means for describing the various
physical and chemical parameters of materials in quantitative
terms.
Eg. 10cm of an object implies that the object is 10 times as large as 1cm etc….

11. Types of Measurements
Measurement: There are various instruments available for measurement of
each of the above parameters.
 Pressure: Pressure gauges of various types, Pressure Transmitter's etc.
 Flow: Vortex flow meters, Magnetic flow meters, Turbine flow meters,
Mass flow meters, Venturi flow meters, Orifice flow meters etc.
 Temperature: Resistance Temperature Detectors (RTDs), Thermocouples,
Thermistors, Temperature gauges etc.
 Level: Differential Pressure Transmitters (DPT), Level Trolls, Level gauges,
Rotameters etc.

13. Methods Of Measurement

14. • Direct measurement
The quantity to be measured is determined directly.
Example – Measure distance by scale
• Indirect measurement
The quantity to be measured is not measured directly. But other related
parameter is measured and inference is drawn from there.
Example – Measure distance by optical method where we use telescope to
calculate distance.
I

15. II

17. III Contact Type:
Where the sensing element of measuring device comes as a contact with
medium whose characteristics are being measured.

18. Non-Contact Type:
Where the sensing element does not communicate physically with the
medium.

20. Generalized Measurement System and
Its Functional Elements.

23. Transducer / Sensors….

24. Once again…..Instrumentation
• Aim: Noise or Artificial Errors should not be
there in to the measurements.
• Eg: A B.P. Machine at Doctor , if it is not
calibrates perfectly see what results we get
(Negatively / positively)

25. Classification of measuring
instruments
1. On the basis of mode of measurement
2. On the basis of state of contact of the
instrument with the medium
3. On the basis of nature of signals being
processed.
4. Based on condition of pointer
5. On the basis of power source requirement

26. 1.On the basis of mode of
measurement
i. Primary Measuring instruments
-direct observation
-No translation required
Ex- Scale
ii. Secondary Measuring instruments
-involves only one translation
Ex- bourdon Tube
iii. Tertiary Measuring instruments
-involves two translation
Ex- Thermocouple

27. 2.On the basis of state of contact of
the instrument with the medium
1. CONTACT TYPE
Eg: bourdon tube, thermometer
2. NON- CONTACT TYPE
Eg: Radiation pyrometer

28. 3. On the basis of nature of signals
being processed
1. Anolog measuring instruments:
-Continuous function of time
Eg: mercury thermometer, voltmeter, ammeter
2. Digital measuring instruments:
- Discrete and vary in steps
- Eg: digital thermometer, digital tachometer,
etc.

29. 4. Based on condition of pointer
1. Deflection type measuring instruments
Eg: Ammeter, voltmeter
2. Null type measuring instruments
Pointer is maintained at fixed position while measuring a
physical quantity by balancing it with an equal and opposing
force
Eg: vegitable weighing balance.
Dead weight pressure gauge

30. 5. On the basis of power source
requirement
1. Self sufficient instruments
-External power source not needed.
Eg: Mercury in glass thermometer, Bourdon
tube, Pitot tube
2. Power operated instruments
External power source needed
Eg: LVDT

33. Definition of TRANSDUCER
• A transducer is a device that converts energy from one form
to another. Usually a transducer converts a signal in one form
of energy to a signal in another.
• microphones, loudspeakers, thermometers, position and
pressure sensors, and antenna.

37. Different Transducer elements
• Analog Transducers
• 1] Electro Mechanical Type
---Potential metric Resistance Type
---Inductive
---Capacitive
---Strain/ Displacement

39. STATIC CHARS

40. ACCURACY & PRECISION

41. ACCURACY
• Closeness/conformity to the true value of the
quantity under measurement.
PRECISION
• The ability of the instrument to reproduce it’s
readings or observation again and again for
constant input signal.

42. Both A & P combination

43. Difference b/w accuracy & precision

44. RANGE
• The region B/W the limits within which the instrument is
designed to operate for measuring, indicating or recording a
physical quantity is called Range of Instrument. The range is
expressed by stating the lower and upper values.
SPAN
• This represents the algebraic differences B/W the
upper and lower range values of the instrument.

46. Calibration
• Instrument calibration is one of the primary processes
used to maintain instrument accuracy.
• Calibration is the process of configuring an instrument to
provide a result for a sample within an acceptable range.
• The difference between true value and
measured value is known as measurement
error.
ERRORS
Error = Vt – Vm

47. • Degree of closeness value is called as
reproducibility. In terms of scale readings in a
given period of time it is concerned.
Reproducibility
• Variation of a scale reading deals with
reproducibility. It is random in nature.
Whenever we take same readings should be
produced.
Repeatability

48. Drift
• Drift is defined as the gradual shift in the
indication over a period of time where in the
input variable does not change. This may be
caused due to the environmental factors such
as stray electric fields, stray magnetic fields,
thermal E.M.F’s, mechanical vibrations,
change in temperature etc.

49. or

50. Linearity

51. Sensitivity

52. Resolution
• If the instrument is being used for measurement, there is a
minimum change in the input for which certain detectable
change in the output is observed. This incremental change in
input is known as Resolution.
• It is defined as the smallest increment of the measured value
that can be detected by the instrument.
• The least count of any instrument is taken as the resolution of
the instrument.
• This should be as low as possible.
Ex: Resolution of micrometer is 0.01 mm.

53. Threshold
• The minimum value for which the meter
responds or deflects is known as threshold.
• Both threshold and resolution can’t be zero
due to various factors like inertia in the
moving parts .
Ex: Due to backlash between the gears

54. Hysteresis
• It is the phenomenon
which depicts different
output effects while
loading & unloading .

55. DYNAMIC CHARS

56. Dynamic Response

58. Dynamic Error
• The difference B/W the value indicated by the
measurement system and true value of the
quantity with respect to time is called as
Dynamic Error.

59. Speed Of Response
• It is defined as the rapidity of with which an
instrument responds to the changes in
measured quantity.
Fidelity
• It is defined as the degree to which a
measurement system is capable of faithfully
reproducing the changes in the input, without
any Dynamic error.

60. Measuring “Lag”
• Every system required its own time to respond the
changes in it. This time is called as Lag. It is defined
as the retardation or delay in response of system to
the changes in the input.

61. Extra Definitions may be asked…

63. Types of Errors
• Instrumentation Errors
• Environmental Errors
• Translation & Signal Transmission Errors
• Observation Errors
• Operational Errors
• System Interaction/ Loading Errors

64. Types of Errors
Error: Difference between measured value and true value
1. Gross Errors
2. Systematic Errors:
i. Instrumental Errors
ii. Environmental Errors
iii. Observational Errors
3. Random Errors
Gross Errors: Mainly due to human mistakes in reading
and recording and calculating measurement results
-Due to an oversight
-Due to transposing the reading

65. Gross Error
• Avoided by adopting two means:
1. Great care should be taken in reading and
recording the data.
2. Two, Three or even more readings should be
taken for the quantity under measurement.

66. Instrumental error
i. Due to inherent shortcomings in the
instruments
ii. Due to misuse of instruments
iii. Due to loading effects

67. Due to inherent shortcomings in the
instruments
• May be due to construction, calibration, or
operation of the instruments
• The errors may cause the instrument to read
too low or too high
• Eg:Spiral spring in Permanent magnet
instrument has become weak, reads always
high.

68. Due to misuse of instruments
• Due to fault of the operator
• Due to handling unintelligent way.

69. Due to loading effects
• When connected across a high/ low resistance
circuit.

70. Environmental error
- Including conditions in the area surrounding
the instrument
- May be effects of temp., pressure, humidity,
dust, vibrations etc.

71. Observational error
• Called parallax error

72. 3. Random Errors:
Which are accidental and whose magnitude and
sign cannot be predicted from a knowledge of
the measuring system and condition of
measurement.
You measure the mass of a ring three times
using the same balance and get slightly
different values: 17.46 g, 17.42 g, 17.44 g
Take more data. Random errors can be
evaluated through statistical analysis and can
be reduced by averaging over a large number
of observations.

73. References
• https://www.slideshare.net/Ravi0528/charact
eristics-of-instruments
• https://www.slideshare.net/Digvijaysinhgohil/
mechanical-measurement-75812486

75. End Of PART 1…….

78. THANKING YOU ALL….
WITH BEST
REGARDS…..
KARTHIK ANAND BOLISETTY
(Ph.D.) V.S.S.U.T., M.E. (O.U.), B.Tech (Anurag University) , MIAENG.
Asst. Prof.
Department Of Mechanical Engineering
VIGNANA BHARATHI INSTITUTE OF TECHNOLOGY
Email ID : karthikanand.bolisetty@vbithyd.ac.in
site: vbithyd.ac.in