Industrial Instrumentation

Ch.E- 401
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Course Grading Structure

 Total Credit Hours 3+1=4

Industrial Instrumentation
 Course Outline
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 Introduction
 Fundamentals of Electrical Technology and Digital Logic employed in
measurement.
 Review of Scientific Principles employed in Instrumentation.
 Parts of Instruments e.g. Sensors, Modifiers, Recorders.
 Dynamic & Static properties of instruments.
 Selection & Calibration of Instruments.
 Instrumental Identification and Line Symbols.
 Available technology of Instruments for Temperature, Flow, Level, Weight,
Load, Pressure and Composition.
 Transducers advanced measurement devices employing piezoelectric current,
Ultrasonic, Laser, Microwave. Installation and Installation cost
 Case Studies.

Industrial Instrumentation
 Recommended Books
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 Lessons In Industrial Instrumentation by Tony R. Kuphaldt
 Marlin ,T.E, Process control,2nd Ed.McGraw Hill Book Co., 2000
 Coughanowr D.R and Koppel, C.B. process system analysis & control,
McGraw Hill 1991.
 Process control instrumentation technology, Curtis D. Johnson, Person
Education 2003.
 Considine Douglas M. “Process industrial instruments and controls
Handbook” McGraw Hill Inc.
 Benedict Robert P., “Fundamental of temperature, pressure and flow
measurements”, John Wiley and Sons.
 Industrial Instrumentation_ Principles and Design by Tattamangalam R.
Padmanabhan.
 Industrial Instrumentation and Control by S.K. Singh

Industrial Instrumentation
 Introduction
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 Process instrumentation is a science and an art.
 The ability of instruments to measure and control the process conditions
depend on various features like working principle, cost, installation and
maintenance.
 The term process reference to the operation which must be carried out to create
the desired end product.
 The instruments act as our eyes inside the vessels, pipes, and machines to
convey out side on the control panel or controllers directly.

Industrial Instrumentation
6 General Block Diagram

-Control Valve
-Electric Motor
-Electric Heater
Fluid pressure,
flowrate, temperature,
volume stored etc.

Industrial Instrumentation
Example: Common Home
thermostat
7 Instrumentation Terms
 Process
 Process Variable, or PV
 Set-point, or SP
 Primary Sensing Element, or PSE
 Transducer
 Transmitter
 Zero and Span
 Controller
 Final Control Element (FCE)
 Manipulated Variable (ME)
 Automatic mode
 Manual Mode
Industrial Instrumentation
 Instrumentation Terms (Contd..)
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 Process: The physical system we are attempting to control or measure.
Examples: water filtration system, molten metal casting system, steam
boiler, oil refinery unit, power generation unit.
 Process Variable, or PV: The specific quantity we are measuring in a
process. Examples: pressure, level, temperature, flow, electrical
conductivity, pH, position, speed, vibration.
 Setpoint, or SP: The value at which we desire the process variable to be
maintained at. In other words, the “target” value for the process variable.
 Primary Sensing Element, or PSE: A device directly sensing the
process variable and translating that sensed quantity into an analog
representation (electrical voltage, current, resistance; mechanical force,
motion, etc.). Examples: thermocouple, thermistor, bourdon tube,
microphone, potentiometer, electrochemical cell, accelerometer.

Industrial Instrumentation
9
Instrumentation Terms (Contd..)
 Transducer: A device converting one standardized instrumentation signal into
another standardized instrumentation signal, and/or performing some sort of
processing on that signal. Often referred to as a converter and sometimes as a
“relay.” Examples: I/P converter (converts 4-20 mA electric signal into 3-15
PSI pneumatic signal), P/I converter (converts 3-15 PSI pneumatic signal into
4-20 mA electric signal), square-root extractor (calculates the square root of
the input signal).
 Transmitter: A device translating the signal produced by a primary sensing
element (PSE) into a standardized instrumentation signal such as 3-15 PSI air
pressure, 4-20 mA DC electric current, Fieldbus digital signal packet, etc.,
which may then be conveyed to an indicating device, a controlling device, or
both.

Industrial Instrumentation
10 Instrumentation Terms (Contd..)
 Lower- and Upper-range values, abbreviated LRV and URV,
respectively: the values of process measurement deemed to be 0% and
100% of a transmitter’s calibrated range. For example, if a temperature
transmitter is calibrated to measure a range of temperature starting at 300
degrees Celsius and ending at 500 degrees Celsius, its LRV would be 300
oC and its URV would be 500 oC.

 Zero and Span: alternative descriptions to LRV and URV for the 0% and
100% points of an instrument’s calibrated range. “Zero” refers to the
beginning-point of an instrument’s range (equivalent to LRV), while
“span” refers to the width of its range (URV − LRV). For example, if a
temperature transmitter is calibrated to measure a range of temperature
starting at 300 degrees Celsius and ending at 500 degrees Celsius, its zero
would be 300 oC and its span would be 200 oC.
 Controller: A device receiving a process variable (PV) signal from a
primary sensing element (PSE) or transmitter, comparing that signal to the
setpoint for that process variable, and calculating an appropriate output
signal value to be sent to a final control element (FCE) such as an electric
motor or control valve.
Industrial Instrumentation
11 Instrumentation Terms (Contd..)
 Final Control Element, or FCE: A device receiving the signal output by a
controller to directly influence the process. Examples: variable-speed
electric motor, control valve, electric heater.
 Manipulated Variable, or MV: The quantity in a process we adjust or
otherwise manipulate in order to influence the process variable (PV). Also
used to describe the output signal generated by a controller; i.e. the signal
commanding (“manipulating”) the final control element to influence the
process.
 Automatic mode: When the controller generates an output signal based on
the relationship of process variable (PV) to the setpoint (SP).
 Manual mode: When the controller’s decision-making ability is bypassed
to let a human operator directly determine the output signal sent to the final
control element.

Industrial Instrumentation
 Example (Steam Drum Water Level Control)
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Industrial Instrumentation
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Example (Steam Drum Water Level
Control)

Industrial Instrumentation
14 Example (Steam Drum Water Level
Control)

Industrial Instrumentation
15

The End

Industrial Instrumentation