Information Sheet 2-1: I & C Devices Specification, Function, and Operation
D. LEVEL MEASUREMENT:
I. Level Transducer Selection Checklist
Key questions to ask before selecting a level measurement transducer:
Are you measuring a liquid or solid?
What are the application's temperature and pressure ranges?
Is point level or continuous measurement required?
What level measurement range do you need?
Is the measured material electrically conductive?
Will the material coat or build up on surfaces?
Does turbulence, foam, or vapor occur at the surface of the liquid?
Will you need contact or non-contact level measurement?
What kind of output do you need–analog, relay, digital display, etc.?
II. Types of Level Transducer
Level measurement transducers fall into two main types:
Point level measurement type is used to mark a single discrete liquid height–a
preset level condition. Generally, this type of sensor functions as a high alarm,
signaling an overfill condition, or as a marker for a low alarm condition.
Continuous level measurement type is more sophisticated and can provide level
monitoring of an entire system. They measure fluid level within a range, rather than
at a one point, producing an analog output that directly correlates to the level in the
vessel.
III. Level Transducers
1. Point and continuous level detection for solids
1.1 Vibrating point
1.2 Rotating paddle
1.3 Admittance-type
2. Point level detection of liquids
2.1 Magnetic and mechanical float
2.2 Pneumatic
2.3 Conductive
3. Both for Point Level Detection and Continuous Monitoring of Solids and Liquids
3.1 Capacitance
3.2 Optical interface
3.3 Ultrasonic
3.4 Microwave
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 9
Information Sheet 2-1: I & C Devices Specification, Function, and Operation
4. Continuous level measurement of liquids
4.1 Magneto-restrictive
4.2 Resistive chain
4.3 Hydrostatic pressure
4.4 Air bubbler
4.5 Gamma ray
Note: Refer to Module 1-1 power-point regarding the details of Level Transducers.
E. TEMPERATURE MEASUREMENT:
1. INTRODUCTION:
Temperature is the degree of hotness or coldness of a body measured on a
definite scale.
Temperature Scales:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 10
Information Sheet 2-1: I & C Devices Specification, Function, and Operation
Temperature Scales Conversion:
Principle of Heat Transfer:
The effectiveness and sensitivity of any temperature sensor or transducer is due on the
principle of heat transfer. There are three (3) basic ways how heat transfers:
conduction, convection, and radiation.
1. Mechanical Temp. Sensors/Transducer
Liquid-in-glass thermometers
Filled-System thermometers
Bimetallic thermometers
3. Electrical Temp. Sensors/Transducer
Thermo-voltaic Elements (Thermocouple)
Thermo-resistive Elements
Temperature Sensitive Materials
Pyrometers
Note: Refer to Module 1-1 power-point regarding the details of Mechanical Temp. Sensors /
Transducer and Electrical Temp. Sensors / Transducer.
F. FLOW MEASUREMENT:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 11
Information Sheet 2-1: I & C Devices Specification, Function, and Operation
I. INTRODUCTION:
Flow is actually the amount of fluid that passed a given point. Flow Rate is the
amount of fluid that passed a given point at any given instant, while Total
Flow is the amount of fluid that passed a given point during a specific period
of time.
Units of Flow:
Volume-based – Examples of volume-based metric units are cc/s, mm3/s, m3/hr,
cc/min, etc. English units include gal/s, gal/min (gpm), ft3/s, ft3/min (cfm), ft3/day,
etc.
Mass-based – Examples of mass-based metric units are g/s, kg/s, kg/min,
kg/hr, etc. English units include oz/s, lb/hr (pph), tons/hr (tph), etc.
II. OPEN CHANNEL FLOW SENSOR/TRANSDUCER
This type of flow measurement is applicable in irrigation systems, dams, water
treatment facilities, desalination plants, etc. It basic principle is forcing the fluid
to pass a specific design of barrier and measuring the rise of its level in an
adjacent still-well, the higher the level at the still-well, the higher also the flow-
rate.
WEIR
FLUME
III. ENCLOSED PIPE FLOW SENSOR/TRANSDUCER
HEAD FLOWMETER
POSITIVE DISPLACEMENT FLOWMETER
VELOCITY FLOWMETER
MASS FLOWMETER
Note: Refer to Module 1-1 power-point regarding the details of Open channel Flow Sensors /
Transducer and Enclosed channel Flow Sensors / Transducer.
G. SUMMARY:
In interpreting work instructions regarding the installation of I&C devices, a technician must have
the knowledge of the fundamentals of instrumentation and control technology. These are
contained in this information sheet.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 12
Worksheet 2-1: I & C Devices Specification, Function, and Operation
Learning outcome:
Describe instrumentation and control devices according to specification, function, and
operation.
Learning Activity:
Define and explain instrumentation and control devices manuals and specification
sheet.
CONTENTS:
A. Introduction
B. Definition of terms
C. Pressure measurement
D. Level measurement
E. Temperature measurement
F. Flow measurement
G. Summary
A. INTRODUCTION:
Have you seen the 80s movie, Rocobop? Well, it’s about this cop who was badly shot in one of
police operations, and in order to save him, he was made into cyborg, partly human and partly
machine. This concept is the principle behind any industrial automation system, where man
and machine use their best qualities for a common cause to improve the manufacturing,
maintenance, etc., and ultimately the existence of all living creatures.
Industrial automation has many allied technologies and one of them is Instrumentation and
control (I&C). One of the main tasks of an I&C technician is to install instrumentation and
control devices. And, its most important sub-task is to interpret work instructions related to
installation of I&C devices.
This information sheet contains the fundamentals of instrumentation and control technology
which are essential in the interpretation of work instructions.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 1
Worksheet 2-1: I & C Devices Specification, Function, and Operation
B. DEFINITION OF TERMS
1. Industrial Automation is a step beyond mechanization. Whereas mechanization provided
human operators with machinery to assist them with the muscular requirements of work,
industrial automation greatly reduces the need for human sensory and mental
requirements as well. Industrial automation has two main categories, machine automation
and process automation.
2. Mechatronics is the synergistic combination of mechanical, electronics/electrical, and
computer software engineering to automate a mechanize control system. It can be referred
to as machine automation.
3. Machine Automation are applicable for semiconductor manufacturing, building automation,
construction machineries, transportation controls (land, sea, air, space)
product packaging machineries, mining equipment controls, etc.
4. Instrumentation is collection of instruments or their application for the purpose of
observation, measurement or control. It can be referred to as process automation.
5. Process Automation is applicable for food processing, biomedical processes petrochemical
refinery, water treatment, pollution control, power generation, etc.
6. Observation is the output of the 5 senses of man. It is expressed in terms of qualitative
characteristics of a physical object or variable. In process automation, observation is derived
from the output of sensors. Figure – 1 below compares man’s senses to machine’s primary
elements.
7. Measurement is the output of man using a tool to determine qualitative and quantitative
characteristics of a physical object/variable. In process automation, measurement is the
output sensors connected to a transducer, indicator, and recorder. From Figure -1, we can
say that measurement is the product of senses and brain (primary and intermediate
elements).
8. Control is the output when man operates using his senses to observe an object or variable,
then use his intellect to give meaning and decide on a course of action, and finally use his
motor faculties to execute his course of action. In Figure – 1, it happens when the machine
elements operates to detect, process, react, and correct changes in control loop variables.
Note: Instrumentation and control is often defined separately because there are some
systems that do not involve observation and control, only observation and measurement.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 2
Worksheet 2-1: I & C Devices Specification, Function, and Operation
AUTOMATIC CONTROL CONCEPT
MAN MACHINE
I. SENSES I. PRIMARY ELEMENT
• Eyes • Photocells
• Ears • Microphone
• Nose • Smoke Detectors
• Skin / Touch • Thermometers
• Tongue • Analytical Sensors
II. BRAIN II. INTERMEDIATE
• Intellect ELEMENT
• Will • Indicators
• Recorders
III. MOTOR FACULTIES • Controllers
• Hands
• Feet III. FINAL ELEMENT
• Body • Motors
Figure 1 – 1 • Cylinders
9. CONTROL SYSTEMS / LOOPS:
Figure 1 – 2 and Figure 1 – 3 shows a typical heat exchanger control loops.
The close loop has feedback. The intervention of the operator is less because it’s fully
automatic.
The open loop has no feedback coming from the sensor and transmitter. Any changes
in controlled variable rely on the operator. This can be referred to as semi – automatic.
Figure 1 – 2: Close Loop Figure 1 – 3: Open Loop
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 3
Worksheet 2-1: I & C Devices Specification, Function, and Operation
10. CONTROL LOOP VARIABLES:
Independent variables (IV) answer the question "What do I change?" In Figure 1 – 2,
the flow of the steam is the IV.
Dependent variables (DV) answer the question "What do I observe?" In Figure 1 – 2,
the temperature of the water going out of the heat exchanger is the DV.
Controlled variables (CV) answer the question "What do I keep the same?" In Figure 1
– 2, the temperature of the water inside the heat exchanger is the CV.
Extraneous variables (EV) answer the question "What uninteresting variables might
mediate the effect of the Independent Variable on the Dependent Variable?" In Figure 1
– 3, the disturbances (energy loss and gain) in and out of the heat exchanger is the
EV.
11. PROCESS VARIABLES:
Process variables are the objects of process automation (instrumentation and control).
There are 4 Basic Process Variables; Pressure, Level, Temperature, and Flow.
Other process variables such as density, force or weight, etc. can be derived from the
basic process variables.
12. ELEMENTS OF PROCESS CONTROL:
Primary Elements senses or detects the control loop variables. In Figure 1 – 2, the
primary elements are the transducers - sensors and transmitter.
Intermediate Elements receive signals from primary elements and provide
corresponding output signal either through indication/record or control action. In Figure 1
– 2, the intermediate elements are controller, recorder, and enunciator.
Final Elements receive signals from a controller and execute corrective action to
manipulated variable. In Figure 1 – 2, the final element is the control valve.
Note:
With the current innovations in automation engineering and technology, instrumentation and
control devices manufacturers combine the functionalities of the different elements of process
control, for instance:
Some instrumentation and control devices have primary, intermediate, and final
elements in 1 unit.
Some instrumentation and control devices have primary and intermediate elements, and
some instrumentation and control devices have intermediate and final elements.
13. TRANSDUCER:
A transducer is a device, electrical, electronic, electro-mechanical, electromagnetic,
photonic, or photovoltaic, that converts one type of energy or physical attribute to
another for various purposes including measurement or information transfer.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 4
Worksheet 2-1: I & C Devices Specification, Function, and Operation
14. SENSORS:
A sensor is a device that measures a physical quantity and converts it into a signal
which can be read by an observer or by an instrument.
Types of sensor; self – generating, and passive.
Characteristics of sensor:
a. A good or ideal sensor is designed to be linear. The output signal of such a sensor is
linearly proportional to the value of the measured property.
b. If the output signal is not zero when the measured property is zero, the sensor has
an offset or bias. This is defined as the output of the sensor at zero input.
c. The sensitivity or gain is then defined as the ratio between output signal and
measured property. If the sensitivity is not constant over the range of the sensor, this
is called nonlinearity.
d. If the output signal slowly changes independent of the measured property, this is
defined as drift.
e. If the sensor has a digital output, the output is essentially an approximation of the
measured property. The approximation error is also called digitization error.
15. TRANSMITTER:
In industrial process control, a "transmitter" is any device which converts measurements
from a sensor into a signal to be received, usually sent via wires, by some display or
control device located a distance away.
C. PRESSURE MEASUREMENT:
I. INTRODUCTION
WHAT IS PRESSURE?
ATMOSPHERIC PRESSURE
HYDROSTATIC PRESSURE
MODES OF PRESSURE
II. PRESSURE SENSORS/TRANSDUCERS
BOURDON TUBE
SPRING AND PISTON
BELLOWS AND CAPSULES
DIAPHRAGM
III. ELECTRICAL PRESSURE TRANSDUCERS
PIEZO-RESISTIVE STRAIN GAUGE
CAPACITIVE
ELECTROMAGNETIC
OPTICAL
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 5
Worksheet 2-1: I & C Devices Specification, Function, and Operation
I. INTRODUCTION
Pressure is defined as a force per unit area, or is the force exerted by an object on a
certain area. Pressure results from molecules exerting a force by impacting over a
defined area. The relationship is given by:
Pressure (P) = Force (F)
Area (A)
Atmospheric pressure is the amount of pressure that a column of air exerts on a body
due to the influence of gravity.
Vacuum is a volume of space that is essentially empty of matter, such that its gaseous
pressure is much less than atmospheric pressure. Vacuum pressure is pressure lower
than atmospheric pressure.
Hydrostatic pressure is the amount of pressure that a column of liquid exerts on a body
due to the influence of gravity.
Pressure (P) =Specific Gravity (S.G.) * Height (H)
The objects of pressure measurements are gas, liquid, and steam.
Modes of pressure measurement:
\ Install (ICD) Date: Developed Date: Revised Page #
Instrumentation and Control Devices April 27, 2010 6
Code No.
ECL724301
Worksheet 2-1: I & C Devices Specification, Function, and Operation
II. MECHANICAL PRESSURE SENSOR/TRANSDUCER
Bellows
Bourdon Piston
III. ELECTRICAL PRESSURE TRANSDUCER
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 7
Worksheet 2-1: I & C Devices Specification, Function, and Operation
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 8
Worksheet 2-1: I & C Devices Specification, Function, and Operation
D. LEVEL MEASUREMENT:
I. Level Transducer Selection Checklist
Key questions to ask before selecting a level measurement transducer:
Are you measuring a liquid or solid?
What are the application's temperature and pressure ranges?
Is point level or continuous measurement required?
What level measurement range do you need?
Is the measured material electrically conductive?
Will the material coat or build up on surfaces?
Does turbulence, foam, or vapor occur at the surface of the liquid?
Will you need contact or non-contact level measurement?
What kind of output do you need–analog, relay, digital display, etc.?
II. Types of Level Transducer
Level measurement transducers fall into two main types:
Point level measurement type is used to mark a single discrete liquid height–a
preset level condition. Generally, this type of sensor functions as a high alarm,
signaling an overfill condition, or as a marker for a low alarm condition.
Continuous level measurement type is more sophisticated and can provide level
monitoring of an entire system. They measure fluid level within a range, rather than
at a one point, producing an analog output that directly correlates to the level in the
vessel.
III. Level Transducers
1. Point and continuous level detection for solids
1.1 Vibrating point
1.2 Rotating paddle
1.3 Admittance-type
2. Point level detection of liquids
2.1 Magnetic and mechanical float
2.2 Pneumatic
2.3 Conductive
3. Both for Point Level Detection and Continuous Monitoring of Solids and Liquids
3.1 Capacitance
3.2 Optical interface
3.3 Ultrasonic
3.4 Microwave
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 9
Worksheet 2-1: I & C Devices Specification, Function, and Operation
4. Continuous level measurement of liquids
4.1 Magneto-restrictive
4.2 Resistive chain
4.3 Hydrostatic pressure
4.4 Air bubbler
4.5 Gamma ray
Note: Refer to Module 1-1 power-point regarding the details of Level Transducers.
E. TEMPERATURE MEASUREMENT:
1. INTRODUCTION:
Temperature is the degree of hotness or coldness of a body measured on a
definite scale.
Temperature Scales:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 10
Worksheet 2-1: I & C Devices Specification, Function, and Operation
Temperature Scales Conversion:
Principle of Heat Transfer:
The effectiveness and sensitivity of any temperature sensor or transducer is due on the
principle of heat transfer. There are three (3) basic ways how heat transfers:
conduction, convection, and radiation.
1. Mechanical Temp. Sensors/Transducer
Liquid-in-glass thermometers
Filled-System thermometers
Bimetallic thermometers
3. Electrical Temp. Sensors/Transducer
Thermo-voltaic Elements (Thermocouple)
Thermo-resistive Elements
Temperature Sensitive Materials
Pyrometers
Note: Refer to Module 1-1 power-point regarding the details of Mechanical Temp. Sensors /
Transducer and Electrical Temp. Sensors / Transducer.
F. FLOW MEASUREMENT:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 11
Worksheet 2-1: I & C Devices Specification, Function, and Operation
I. INTRODUCTION:
Flow is actually the amount of fluid that passed a given point. Flow Rate is the
amount of fluid that passed a given point at any given instant, while Total
Flow is the amount of fluid that passed a given point during a specific period
of time.
Units of Flow:
Volume-based – Examples of volume-based metric units are cc/s, mm3/s, m3/hr,
cc/min, etc. English units include gal/s, gal/min (gpm), ft3/s, ft3/min (cfm), ft3/day,
etc.
Mass-based – Examples of mass-based metric units are g/s, kg/s, kg/min,
kg/hr, etc. English units include oz/s, lb/hr (pph), tons/hr (tph), etc.
II. OPEN CHANNEL FLOW SENSOR/TRANSDUCER
This type of flow measurement is applicable in irrigation systems, dams, water
treatment facilities, desalination plants, etc. It basic principle is forcing the fluid
to pass a specific design of barrier and measuring the rise of its level in an
adjacent still-well, the higher the level at the still-well, the higher also the flow-
rate.
WEIR
FLUME
III. ENCLOSED PIPE FLOW SENSOR/TRANSDUCER
HEAD FLOWMETER
POSITIVE DISPLACEMENT FLOWMETER
VELOCITY FLOWMETER
MASS FLOWMETER
Note: Refer to Module 1-1 power-point regarding the details of Open channel Flow Sensors /
Transducer and Enclosed channel Flow Sensors / Transducer.
G. SUMMARY:
In interpreting work instructions regarding the installation of I&C devices, a technician must have
the knowledge of the fundamentals of instrumentation and control technology. These are
contained in this information sheet.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 12
Information Sheet 3-1: Tools, Materials, and Equipment
Learning outcome:
Use the necessary tools, material, and equipment needed in installing
instrumentation and control devices.
Learning Activity:
Enumerate the necessary tools, materials, and equipment needed in installing an
instrumentation and control devices.
Use properly tools, materials, and equipment needed in installing an instrumentation
and control devices.
CONTENTS:
A. Introduction
B. Definition of terms
C. Pressure measurement
D. Level measurement
E. Temperature measurement
F. Flow measurement
G. Summary
A. INTRODUCTION:
Have you seen the 80s movie, Rocobop? Well, it’s about this cop who was badly shot in one of
police operations, and in order to save him, he was made into cyborg, partly human and partly
machine. This concept is the principle behind any industrial automation system, where man
and machine use their best qualities for a common cause to improve the manufacturing,
maintenance, etc., and ultimately the existence of all living creatures.
Industrial automation has many allied technologies and one of them is Instrumentation and
control (I&C). One of the main tasks of an I&C technician is to install instrumentation and
control devices. And, its most important sub-task is to interpret work instructions related to
installation of I&C devices.
This information sheet contains the fundamentals of instrumentation and control technology
which are essential in the interpretation of work instructions.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 1
Information Sheet 3-1: Tools, Materials, and Equipment
B. DEFINITION OF TERMS
1. Industrial Automation is a step beyond mechanization. Whereas mechanization provided
human operators with machinery to assist them with the muscular requirements of work,
industrial automation greatly reduces the need for human sensory and mental
requirements as well. Industrial automation has two main categories, machine automation
and process automation.
2. Mechatronics is the synergistic combination of mechanical, electronics/electrical, and
computer software engineering to automate a mechanize control system. It can be referred
to as machine automation.
3. Machine Automation are applicable for semiconductor manufacturing, building automation,
construction machineries, transportation controls (land, sea, air, space)
product packaging machineries, mining equipment controls, etc.
4. Instrumentation is collection of instruments or their application for the purpose of
observation, measurement or control. It can be referred to as process automation.
5. Process Automation is applicable for food processing, biomedical processes petrochemical
refinery, water treatment, pollution control, power generation, etc.
6. Observation is the output of the 5 senses of man. It is expressed in terms of qualitative
characteristics of a physical object or variable. In process automation, observation is derived
from the output of sensors. Figure – 1 below compares man’s senses to machine’s primary
elements.
7. Measurement is the output of man using a tool to determine qualitative and quantitative
characteristics of a physical object/variable. In process automation, measurement is the
output sensors connected to a transducer, indicator, and recorder. From Figure -1, we can
say that measurement is the product of senses and brain (primary and intermediate
elements).
8. Control is the output when man operates using his senses to observe an object or variable,
then use his intellect to give meaning and decide on a course of action, and finally use his
motor faculties to execute his course of action. In Figure – 1, it happens when the machine
elements operates to detect, process, react, and correct changes in control loop variables.
Note: Instrumentation and control is often defined separately because there are some
systems that do not involve observation and control, only observation and measurement.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 2
Information Sheet 3-1: Tools, Materials, and Equipment
AUTOMATIC CONTROL CONCEPT
MAN MACHINE
I. SENSES I. PRIMARY ELEMENT
• Eyes • Photocells
• Ears • Microphone
• Nose • Smoke Detectors
• Skin / Touch • Thermometers
• Tongue • Analytical Sensors
II. BRAIN II. INTERMEDIATE
• Intellect ELEMENT
• Will • Indicators
• Recorders
III. MOTOR FACULTIES • Controllers
• Hands
• Feet III. FINAL ELEMENT
• Body • Motors
Figure 1 – 1 • Cylinders
9. CONTROL SYSTEMS / LOOPS:
Figure 1 – 2 and Figure 1 – 3 shows a typical heat exchanger control loops.
The close loop has feedback. The intervention of the operator is less because it’s fully
automatic.
The open loop has no feedback coming from the sensor and transmitter. Any changes
in controlled variable rely on the operator. This can be referred to as semi – automatic.
Figure 1 – 2: Close Loop Figure 1 – 3: Open Loop
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 3
Information Sheet 3-1: Tools, Materials, and Equipment
10. CONTROL LOOP VARIABLES:
Independent variables (IV) answer the question "What do I change?" In Figure 1 – 2,
the flow of the steam is the IV.
Dependent variables (DV) answer the question "What do I observe?" In Figure 1 – 2,
the temperature of the water going out of the heat exchanger is the DV.
Controlled variables (CV) answer the question "What do I keep the same?" In Figure 1
– 2, the temperature of the water inside the heat exchanger is the CV.
Extraneous variables (EV) answer the question "What uninteresting variables might
mediate the effect of the Independent Variable on the Dependent Variable?" In Figure 1
– 3, the disturbances (energy loss and gain) in and out of the heat exchanger is the
EV.
11. PROCESS VARIABLES:
Process variables are the objects of process automation (instrumentation and control).
There are 4 Basic Process Variables; Pressure, Level, Temperature, and Flow.
Other process variables such as density, force or weight, etc. can be derived from the
basic process variables.
12. ELEMENTS OF PROCESS CONTROL:
Primary Elements senses or detects the control loop variables. In Figure 1 – 2, the
primary elements are the transducers - sensors and transmitter.
Intermediate Elements receive signals from primary elements and provide
corresponding output signal either through indication/record or control action. In Figure 1
– 2, the intermediate elements are controller, recorder, and enunciator.
Final Elements receive signals from a controller and execute corrective action to
manipulated variable. In Figure 1 – 2, the final element is the control valve.
Note:
With the current innovations in automation engineering and technology, instrumentation and
control devices manufacturers combine the functionalities of the different elements of process
control, for instance:
Some instrumentation and control devices have primary, intermediate, and final
elements in 1 unit.
Some instrumentation and control devices have primary and intermediate elements, and
some instrumentation and control devices have intermediate and final elements.
13. TRANSDUCER:
A transducer is a device, electrical, electronic, electro-mechanical, electromagnetic,
photonic, or photovoltaic, that converts one type of energy or physical attribute to
another for various purposes including measurement or information transfer.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 4
Information Sheet 3-1: Tools, Materials, and Equipment
14. SENSORS:
A sensor is a device that measures a physical quantity and converts it into a signal
which can be read by an observer or by an instrument.
Types of sensor; self – generating, and passive.
Characteristics of sensor:
a. A good or ideal sensor is designed to be linear. The output signal of such a sensor is
linearly proportional to the value of the measured property.
b. If the output signal is not zero when the measured property is zero, the sensor has
an offset or bias. This is defined as the output of the sensor at zero input.
c. The sensitivity or gain is then defined as the ratio between output signal and
measured property. If the sensitivity is not constant over the range of the sensor, this
is called nonlinearity.
d. If the output signal slowly changes independent of the measured property, this is
defined as drift.
e. If the sensor has a digital output, the output is essentially an approximation of the
measured property. The approximation error is also called digitization error.
15. TRANSMITTER:
In industrial process control, a "transmitter" is any device which converts measurements
from a sensor into a signal to be received, usually sent via wires, by some display or
control device located a distance away.
C. PRESSURE MEASUREMENT:
I. INTRODUCTION
WHAT IS PRESSURE?
ATMOSPHERIC PRESSURE
HYDROSTATIC PRESSURE
MODES OF PRESSURE
II. PRESSURE SENSORS/TRANSDUCERS
BOURDON TUBE
SPRING AND PISTON
BELLOWS AND CAPSULES
DIAPHRAGM
III. ELECTRICAL PRESSURE TRANSDUCERS
PIEZO-RESISTIVE STRAIN GAUGE
CAPACITIVE
ELECTROMAGNETIC
OPTICAL
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 5
Information Sheet 3-1: Tools, Materials, and Equipment
I. INTRODUCTION
Pressure is defined as a force per unit area, or is the force exerted by an object on a
certain area. Pressure results from molecules exerting a force by impacting over a
defined area. The relationship is given by:
Pressure (P) = Force (F)
Area (A)
Atmospheric pressure is the amount of pressure that a column of air exerts on a body
due to the influence of gravity.
Vacuum is a volume of space that is essentially empty of matter, such that its gaseous
pressure is much less than atmospheric pressure. Vacuum pressure is pressure lower
than atmospheric pressure.
Hydrostatic pressure is the amount of pressure that a column of liquid exerts on a body
due to the influence of gravity.
Pressure (P) =Specific Gravity (S.G.) * Height (H)
The objects of pressure measurements are gas, liquid, and steam.
Modes of pressure measurement:
\ Install (ICD) Date: Developed Date: Revised Page #
Instrumentation and Control Devices April 27, 2010 6
Code No.
ECL724301
Information Sheet 3-1: Tools, Materials, and Equipment
II. MECHANICAL PRESSURE SENSOR/TRANSDUCER
Bellows
Bourdon Piston
III. ELECTRICAL PRESSURE TRANSDUCER
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 7
Information Sheet 3-1: Tools, Materials, and Equipment
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 8
Information Sheet 3-1: Tools, Materials, and Equipment
D. LEVEL MEASUREMENT:
I. Level Transducer Selection Checklist
Key questions to ask before selecting a level measurement transducer:
Are you measuring a liquid or solid?
What are the application's temperature and pressure ranges?
Is point level or continuous measurement required?
What level measurement range do you need?
Is the measured material electrically conductive?
Will the material coat or build up on surfaces?
Does turbulence, foam, or vapor occur at the surface of the liquid?
Will you need contact or non-contact level measurement?
What kind of output do you need–analog, relay, digital display, etc.?
II. Types of Level Transducer
Level measurement transducers fall into two main types:
Point level measurement type is used to mark a single discrete liquid height–a
preset level condition. Generally, this type of sensor functions as a high alarm,
signaling an overfill condition, or as a marker for a low alarm condition.
Continuous level measurement type is more sophisticated and can provide level
monitoring of an entire system. They measure fluid level within a range, rather than
at a one point, producing an analog output that directly correlates to the level in the
vessel.
III. Level Transducers
1. Point and continuous level detection for solids
1.1 Vibrating point
1.2 Rotating paddle
1.3 Admittance-type
2. Point level detection of liquids
2.1 Magnetic and mechanical float
2.2 Pneumatic
2.3 Conductive
3. Both for Point Level Detection and Continuous Monitoring of Solids and Liquids
3.1 Capacitance
3.2 Optical interface
3.3 Ultrasonic
3.4 Microwave
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 9
Information Sheet 3-1: Tools, Materials, and Equipment
4. Continuous level measurement of liquids
4.1 Magneto-restrictive
4.2 Resistive chain
4.3 Hydrostatic pressure
4.4 Air bubbler
4.5 Gamma ray
Note: Refer to Module 1-1 power-point regarding the details of Level Transducers.
E. TEMPERATURE MEASUREMENT:
1. INTRODUCTION:
Temperature is the degree of hotness or coldness of a body measured on a
definite scale.
Temperature Scales:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 10
Information Sheet 3-1: Tools, Materials, and Equipment
Temperature Scales Conversion:
Principle of Heat Transfer:
The effectiveness and sensitivity of any temperature sensor or transducer is due on the
principle of heat transfer. There are three (3) basic ways how heat transfers:
conduction, convection, and radiation.
1. Mechanical Temp. Sensors/Transducer
Liquid-in-glass thermometers
Filled-System thermometers
Bimetallic thermometers
3. Electrical Temp. Sensors/Transducer
Thermo-voltaic Elements (Thermocouple)
Thermo-resistive Elements
Temperature Sensitive Materials
Pyrometers
Note: Refer to Module 1-1 power-point regarding the details of Mechanical Temp. Sensors /
Transducer and Electrical Temp. Sensors / Transducer.
F. FLOW MEASUREMENT:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 11
Information Sheet 3-1: Tools, Materials, and Equipment
I. INTRODUCTION:
Flow is actually the amount of fluid that passed a given point. Flow Rate is the
amount of fluid that passed a given point at any given instant, while Total
Flow is the amount of fluid that passed a given point during a specific period
of time.
Units of Flow:
Volume-based – Examples of volume-based metric units are cc/s, mm3/s, m3/hr,
cc/min, etc. English units include gal/s, gal/min (gpm), ft3/s, ft3/min (cfm), ft3/day,
etc.
Mass-based – Examples of mass-based metric units are g/s, kg/s, kg/min,
kg/hr, etc. English units include oz/s, lb/hr (pph), tons/hr (tph), etc.
II. OPEN CHANNEL FLOW SENSOR/TRANSDUCER
This type of flow measurement is applicable in irrigation systems, dams, water
treatment facilities, desalination plants, etc. It basic principle is forcing the fluid
to pass a specific design of barrier and measuring the rise of its level in an
adjacent still-well, the higher the level at the still-well, the higher also the flow-
rate.
WEIR
FLUME
III. ENCLOSED PIPE FLOW SENSOR/TRANSDUCER
HEAD FLOWMETER
POSITIVE DISPLACEMENT FLOWMETER
VELOCITY FLOWMETER
MASS FLOWMETER
Note: Refer to Module 1-1 power-point regarding the details of Open channel Flow Sensors /
Transducer and Enclosed channel Flow Sensors / Transducer.
G. SUMMARY:
In interpreting work instructions regarding the installation of I&C devices, a technician must have
the knowledge of the fundamentals of instrumentation and control technology. These are
contained in this information sheet.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 12
Worksheet 3-1: Tools, Materials, and Equipment
Learning outcome:
Use the necessary tools, material, and equipment needed in installing
instrumentation and control devices.
Learning Activity:
Enumerate the necessary tools, materials, and equipment needed in installing an
instrumentation and control devices.
Use properly tools, materials, and equipment needed in installing an instrumentation
and control devices.
CONTENTS:
A. Introduction
B. Definition of terms
C. Pressure measurement
D. Level measurement
E. Temperature measurement
F. Flow measurement
G. Summary
A. INTRODUCTION:
Have you seen the 80s movie, Rocobop? Well, it’s about this cop who was badly shot in one of
police operations, and in order to save him, he was made into cyborg, partly human and partly
machine. This concept is the principle behind any industrial automation system, where man
and machine use their best qualities for a common cause to improve the manufacturing,
maintenance, etc., and ultimately the existence of all living creatures.
Industrial automation has many allied technologies and one of them is Instrumentation and
control (I&C). One of the main tasks of an I&C technician is to install instrumentation and
control devices. And, its most important sub-task is to interpret work instructions related to
installation of I&C devices.
This information sheet contains the fundamentals of instrumentation and control technology
which are essential in the interpretation of work instructions.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 1
Worksheet 3-1: Tools, Materials, and Equipment
B. DEFINITION OF TERMS
1. Industrial Automation is a step beyond mechanization. Whereas mechanization provided
human operators with machinery to assist them with the muscular requirements of work,
industrial automation greatly reduces the need for human sensory and mental
requirements as well. Industrial automation has two main categories, machine automation
and process automation.
2. Mechatronics is the synergistic combination of mechanical, electronics/electrical, and
computer software engineering to automate a mechanize control system. It can be referred
to as machine automation.
3. Machine Automation are applicable for semiconductor manufacturing, building automation,
construction machineries, transportation controls (land, sea, air, space)
product packaging machineries, mining equipment controls, etc.
4. Instrumentation is collection of instruments or their application for the purpose of
observation, measurement or control. It can be referred to as process automation.
5. Process Automation is applicable for food processing, biomedical processes petrochemical
refinery, water treatment, pollution control, power generation, etc.
6. Observation is the output of the 5 senses of man. It is expressed in terms of qualitative
characteristics of a physical object or variable. In process automation, observation is derived
from the output of sensors. Figure – 1 below compares man’s senses to machine’s primary
elements.
7. Measurement is the output of man using a tool to determine qualitative and quantitative
characteristics of a physical object/variable. In process automation, measurement is the
output sensors connected to a transducer, indicator, and recorder. From Figure -1, we can
say that measurement is the product of senses and brain (primary and intermediate
elements).
8. Control is the output when man operates using his senses to observe an object or variable,
then use his intellect to give meaning and decide on a course of action, and finally use his
motor faculties to execute his course of action. In Figure – 1, it happens when the machine
elements operates to detect, process, react, and correct changes in control loop variables.
Note: Instrumentation and control is often defined separately because there are some
systems that do not involve observation and control, only observation and measurement.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 2
Worksheet 3-1: Tools, Materials, and Equipment
AUTOMATIC CONTROL CONCEPT
MAN MACHINE
I. SENSES I. PRIMARY ELEMENT
• Eyes • Photocells
• Ears • Microphone
• Nose • Smoke Detectors
• Skin / Touch • Thermometers
• Tongue • Analytical Sensors
II. BRAIN II. INTERMEDIATE
• Intellect ELEMENT
• Will • Indicators
• Recorders
III. MOTOR FACULTIES • Controllers
• Hands
• Feet III. FINAL ELEMENT
• Body • Motors
Figure 1 – 1 • Cylinders
9. CONTROL SYSTEMS / LOOPS:
Figure 1 – 2 and Figure 1 – 3 shows a typical heat exchanger control loops.
The close loop has feedback. The intervention of the operator is less because it’s fully
automatic.
The open loop has no feedback coming from the sensor and transmitter. Any changes
in controlled variable rely on the operator. This can be referred to as semi – automatic.
Figure 1 – 2: Close Loop Figure 1 – 3: Open Loop
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 3
Worksheet 3-1: Tools, Materials, and Equipment
10. CONTROL LOOP VARIABLES:
Independent variables (IV) answer the question "What do I change?" In Figure 1 – 2,
the flow of the steam is the IV.
Dependent variables (DV) answer the question "What do I observe?" In Figure 1 – 2,
the temperature of the water going out of the heat exchanger is the DV.
Controlled variables (CV) answer the question "What do I keep the same?" In Figure 1
– 2, the temperature of the water inside the heat exchanger is the CV.
Extraneous variables (EV) answer the question "What uninteresting variables might
mediate the effect of the Independent Variable on the Dependent Variable?" In Figure 1
– 3, the disturbances (energy loss and gain) in and out of the heat exchanger is the
EV.
11. PROCESS VARIABLES:
Process variables are the objects of process automation (instrumentation and control).
There are 4 Basic Process Variables; Pressure, Level, Temperature, and Flow.
Other process variables such as density, force or weight, etc. can be derived from the
basic process variables.
12. ELEMENTS OF PROCESS CONTROL:
Primary Elements senses or detects the control loop variables. In Figure 1 – 2, the
primary elements are the transducers - sensors and transmitter.
Intermediate Elements receive signals from primary elements and provide
corresponding output signal either through indication/record or control action. In Figure 1
– 2, the intermediate elements are controller, recorder, and enunciator.
Final Elements receive signals from a controller and execute corrective action to
manipulated variable. In Figure 1 – 2, the final element is the control valve.
Note:
With the current innovations in automation engineering and technology, instrumentation and
control devices manufacturers combine the functionalities of the different elements of process
control, for instance:
Some instrumentation and control devices have primary, intermediate, and final
elements in 1 unit.
Some instrumentation and control devices have primary and intermediate elements, and
some instrumentation and control devices have intermediate and final elements.
13. TRANSDUCER:
A transducer is a device, electrical, electronic, electro-mechanical, electromagnetic,
photonic, or photovoltaic, that converts one type of energy or physical attribute to
another for various purposes including measurement or information transfer.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 4
Worksheet 3-1: Tools, Materials, and Equipment
14. SENSORS:
A sensor is a device that measures a physical quantity and converts it into a signal
which can be read by an observer or by an instrument.
Types of sensor; self – generating, and passive.
Characteristics of sensor:
a. A good or ideal sensor is designed to be linear. The output signal of such a sensor is
linearly proportional to the value of the measured property.
b. If the output signal is not zero when the measured property is zero, the sensor has
an offset or bias. This is defined as the output of the sensor at zero input.
c. The sensitivity or gain is then defined as the ratio between output signal and
measured property. If the sensitivity is not constant over the range of the sensor, this
is called nonlinearity.
d. If the output signal slowly changes independent of the measured property, this is
defined as drift.
e. If the sensor has a digital output, the output is essentially an approximation of the
measured property. The approximation error is also called digitization error.
15. TRANSMITTER:
In industrial process control, a "transmitter" is any device which converts measurements
from a sensor into a signal to be received, usually sent via wires, by some display or
control device located a distance away.
C. PRESSURE MEASUREMENT:
I. INTRODUCTION
WHAT IS PRESSURE?
ATMOSPHERIC PRESSURE
HYDROSTATIC PRESSURE
MODES OF PRESSURE
II. PRESSURE SENSORS/TRANSDUCERS
BOURDON TUBE
SPRING AND PISTON
BELLOWS AND CAPSULES
DIAPHRAGM
III. ELECTRICAL PRESSURE TRANSDUCERS
PIEZO-RESISTIVE STRAIN GAUGE
CAPACITIVE
ELECTROMAGNETIC
OPTICAL
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 5
Worksheet 3-1: Tools, Materials, and Equipment
I. INTRODUCTION
Pressure is defined as a force per unit area, or is the force exerted by an object on a
certain area. Pressure results from molecules exerting a force by impacting over a
defined area. The relationship is given by:
Pressure (P) = Force (F)
Area (A)
Atmospheric pressure is the amount of pressure that a column of air exerts on a body
due to the influence of gravity.
Vacuum is a volume of space that is essentially empty of matter, such that its gaseous
pressure is much less than atmospheric pressure. Vacuum pressure is pressure lower
than atmospheric pressure.
Hydrostatic pressure is the amount of pressure that a column of liquid exerts on a body
due to the influence of gravity.
Pressure (P) =Specific Gravity (S.G.) * Height (H)
The objects of pressure measurements are gas, liquid, and steam.
Modes of pressure measurement:
\ Install (ICD) Date: Developed Date: Revised Page #
Instrumentation and Control Devices April 27, 2010 6
Code No.
ECL724301
Worksheet 3-1: Tools, Materials, and Equipment
II. MECHANICAL PRESSURE SENSOR/TRANSDUCER
Bellows
Bourdon Piston
III. ELECTRICAL PRESSURE TRANSDUCER
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 7
Worksheet 3-1: Tools, Materials, and Equipment
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 8
Worksheet 3-1: Tools, Materials, and Equipment
D. LEVEL MEASUREMENT:
I. Level Transducer Selection Checklist
Key questions to ask before selecting a level measurement transducer:
Are you measuring a liquid or solid?
What are the application's temperature and pressure ranges?
Is point level or continuous measurement required?
What level measurement range do you need?
Is the measured material electrically conductive?
Will the material coat or build up on surfaces?
Does turbulence, foam, or vapor occur at the surface of the liquid?
Will you need contact or non-contact level measurement?
What kind of output do you need–analog, relay, digital display, etc.?
II. Types of Level Transducer
Level measurement transducers fall into two main types:
Point level measurement type is used to mark a single discrete liquid height–a
preset level condition. Generally, this type of sensor functions as a high alarm,
signaling an overfill condition, or as a marker for a low alarm condition.
Continuous level measurement type is more sophisticated and can provide level
monitoring of an entire system. They measure fluid level within a range, rather than
at a one point, producing an analog output that directly correlates to the level in the
vessel.
III. Level Transducers
1. Point and continuous level detection for solids
1.1 Vibrating point
1.2 Rotating paddle
1.3 Admittance-type
2. Point level detection of liquids
2.1 Magnetic and mechanical float
2.2 Pneumatic
2.3 Conductive
3. Both for Point Level Detection and Continuous Monitoring of Solids and Liquids
3.1 Capacitance
3.2 Optical interface
3.3 Ultrasonic
3.4 Microwave
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 9
Worksheet 3-1: Tools, Materials, and Equipment
4. Continuous level measurement of liquids
4.1 Magneto-restrictive
4.2 Resistive chain
4.3 Hydrostatic pressure
4.4 Air bubbler
4.5 Gamma ray
Note: Refer to Module 1-1 power-point regarding the details of Level Transducers.
E. TEMPERATURE MEASUREMENT:
1. INTRODUCTION:
Temperature is the degree of hotness or coldness of a body measured on a
definite scale.
Temperature Scales:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 10
Worksheet 3-1: Tools, Materials, and Equipment
Temperature Scales Conversion:
Principle of Heat Transfer:
The effectiveness and sensitivity of any temperature sensor or transducer is due on the
principle of heat transfer. There are three (3) basic ways how heat transfers:
conduction, convection, and radiation.
1. Mechanical Temp. Sensors/Transducer
Liquid-in-glass thermometers
Filled-System thermometers
Bimetallic thermometers
3. Electrical Temp. Sensors/Transducer
Thermo-voltaic Elements (Thermocouple)
Thermo-resistive Elements
Temperature Sensitive Materials
Pyrometers
Note: Refer to Module 1-1 power-point regarding the details of Mechanical Temp. Sensors /
Transducer and Electrical Temp. Sensors / Transducer.
F. FLOW MEASUREMENT:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 11
Worksheet 3-1: Tools, Materials, and Equipment
I. INTRODUCTION:
Flow is actually the amount of fluid that passed a given point. Flow Rate is the
amount of fluid that passed a given point at any given instant, while Total
Flow is the amount of fluid that passed a given point during a specific period
of time.
Units of Flow:
Volume-based – Examples of volume-based metric units are cc/s, mm3/s, m3/hr,
cc/min, etc. English units include gal/s, gal/min (gpm), ft3/s, ft3/min (cfm), ft3/day,
etc.
Mass-based – Examples of mass-based metric units are g/s, kg/s, kg/min,
kg/hr, etc. English units include oz/s, lb/hr (pph), tons/hr (tph), etc.
II. OPEN CHANNEL FLOW SENSOR/TRANSDUCER
This type of flow measurement is applicable in irrigation systems, dams, water
treatment facilities, desalination plants, etc. It basic principle is forcing the fluid
to pass a specific design of barrier and measuring the rise of its level in an
adjacent still-well, the higher the level at the still-well, the higher also the flow-
rate.
WEIR
FLUME
III. ENCLOSED PIPE FLOW SENSOR/TRANSDUCER
HEAD FLOWMETER
POSITIVE DISPLACEMENT FLOWMETER
VELOCITY FLOWMETER
MASS FLOWMETER
Note: Refer to Module 1-1 power-point regarding the details of Open channel Flow Sensors /
Transducer and Enclosed channel Flow Sensors / Transducer.
G. SUMMARY:
In interpreting work instructions regarding the installation of I&C devices, a technician must have
the knowledge of the fundamentals of instrumentation and control technology. These are
contained in this information sheet.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 12
Information Sheet 3-2: Personal Protective Equipment
Learning outcome:
Use the necessary personal protective equipment needed in installing
instrumentation and control devices.
Learning Activity:
Enumerate the necessary personal protective equipment needed in installing
instrumentation and control devices.
Use properly the necessary personal protective equipment needed in installing an
instrumentation and control devices.
CONTENTS:
A. Introduction
B. Definition of terms
C. Pressure measurement
D. Level measurement
E. Temperature measurement
F. Flow measurement
G. Summary
A. INTRODUCTION:
Have you seen the 80s movie, Rocobop? Well, it’s about this cop who was badly shot in one of
police operations, and in order to save him, he was made into cyborg, partly human and partly
machine. This concept is the principle behind any industrial automation system, where man
and machine use their best qualities for a common cause to improve the manufacturing,
maintenance, etc., and ultimately the existence of all living creatures.
Industrial automation has many allied technologies and one of them is Instrumentation and
control (I&C). One of the main tasks of an I&C technician is to install instrumentation and
control devices. And, its most important sub-task is to interpret work instructions related to
installation of I&C devices.
This information sheet contains the fundamentals of instrumentation and control technology
which are essential in the interpretation of work instructions.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 1
Information Sheet 3-2: Personal Protective Equipment
B. DEFINITION OF TERMS
1. Industrial Automation is a step beyond mechanization. Whereas mechanization provided
human operators with machinery to assist them with the muscular requirements of work,
industrial automation greatly reduces the need for human sensory and mental
requirements as well. Industrial automation has two main categories, machine automation
and process automation.
2. Mechatronics is the synergistic combination of mechanical, electronics/electrical, and
computer software engineering to automate a mechanize control system. It can be referred
to as machine automation.
3. Machine Automation are applicable for semiconductor manufacturing, building automation,
construction machineries, transportation controls (land, sea, air, space)
product packaging machineries, mining equipment controls, etc.
4. Instrumentation is collection of instruments or their application for the purpose of
observation, measurement or control. It can be referred to as process automation.
5. Process Automation is applicable for food processing, biomedical processes petrochemical
refinery, water treatment, pollution control, power generation, etc.
6. Observation is the output of the 5 senses of man. It is expressed in terms of qualitative
characteristics of a physical object or variable. In process automation, observation is derived
from the output of sensors. Figure – 1 below compares man’s senses to machine’s primary
elements.
7. Measurement is the output of man using a tool to determine qualitative and quantitative
characteristics of a physical object/variable. In process automation, measurement is the
output sensors connected to a transducer, indicator, and recorder. From Figure -1, we can
say that measurement is the product of senses and brain (primary and intermediate
elements).
8. Control is the output when man operates using his senses to observe an object or variable,
then use his intellect to give meaning and decide on a course of action, and finally use his
motor faculties to execute his course of action. In Figure – 1, it happens when the machine
elements operates to detect, process, react, and correct changes in control loop variables.
Note: Instrumentation and control is often defined separately because there are some
systems that do not involve observation and control, only observation and measurement.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 2
Information Sheet 3-2: Personal Protective Equipment
AUTOMATIC CONTROL CONCEPT
MAN MACHINE
I. SENSES I. PRIMARY ELEMENT
• Eyes • Photocells
• Ears • Microphone
• Nose • Smoke Detectors
• Skin / Touch • Thermometers
• Tongue • Analytical Sensors
II. BRAIN II. INTERMEDIATE
• Intellect ELEMENT
• Will • Indicators
• Recorders
III. MOTOR FACULTIES • Controllers
• Hands
• Feet III. FINAL ELEMENT
• Body • Motors
Figure 1 – 1 • Cylinders
9. CONTROL SYSTEMS / LOOPS:
Figure 1 – 2 and Figure 1 – 3 shows a typical heat exchanger control loops.
The close loop has feedback. The intervention of the operator is less because it’s fully
automatic.
The open loop has no feedback coming from the sensor and transmitter. Any changes
in controlled variable rely on the operator. This can be referred to as semi – automatic.
Figure 1 – 2: Close Loop Figure 1 – 3: Open Loop
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 3
Information Sheet 3-2: Personal Protective Equipment
10. CONTROL LOOP VARIABLES:
Independent variables (IV) answer the question "What do I change?" In Figure 1 – 2,
the flow of the steam is the IV.
Dependent variables (DV) answer the question "What do I observe?" In Figure 1 – 2,
the temperature of the water going out of the heat exchanger is the DV.
Controlled variables (CV) answer the question "What do I keep the same?" In Figure 1
– 2, the temperature of the water inside the heat exchanger is the CV.
Extraneous variables (EV) answer the question "What uninteresting variables might
mediate the effect of the Independent Variable on the Dependent Variable?" In Figure 1
– 3, the disturbances (energy loss and gain) in and out of the heat exchanger is the
EV.
11. PROCESS VARIABLES:
Process variables are the objects of process automation (instrumentation and control).
There are 4 Basic Process Variables; Pressure, Level, Temperature, and Flow.
Other process variables such as density, force or weight, etc. can be derived from the
basic process variables.
12. ELEMENTS OF PROCESS CONTROL:
Primary Elements senses or detects the control loop variables. In Figure 1 – 2, the
primary elements are the transducers - sensors and transmitter.
Intermediate Elements receive signals from primary elements and provide
corresponding output signal either through indication/record or control action. In Figure 1
– 2, the intermediate elements are controller, recorder, and enunciator.
Final Elements receive signals from a controller and execute corrective action to
manipulated variable. In Figure 1 – 2, the final element is the control valve.
Note:
With the current innovations in automation engineering and technology, instrumentation and
control devices manufacturers combine the functionalities of the different elements of process
control, for instance:
Some instrumentation and control devices have primary, intermediate, and final
elements in 1 unit.
Some instrumentation and control devices have primary and intermediate elements, and
some instrumentation and control devices have intermediate and final elements.
13. TRANSDUCER:
A transducer is a device, electrical, electronic, electro-mechanical, electromagnetic,
photonic, or photovoltaic, that converts one type of energy or physical attribute to
another for various purposes including measurement or information transfer.
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 4
Information Sheet 3-2: Personal Protective Equipment
14. SENSORS:
A sensor is a device that measures a physical quantity and converts it into a signal
which can be read by an observer or by an instrument.
Types of sensor; self – generating, and passive.
Characteristics of sensor:
a. A good or ideal sensor is designed to be linear. The output signal of such a sensor is
linearly proportional to the value of the measured property.
b. If the output signal is not zero when the measured property is zero, the sensor has
an offset or bias. This is defined as the output of the sensor at zero input.
c. The sensitivity or gain is then defined as the ratio between output signal and
measured property. If the sensitivity is not constant over the range of the sensor, this
is called nonlinearity.
d. If the output signal slowly changes independent of the measured property, this is
defined as drift.
e. If the sensor has a digital output, the output is essentially an approximation of the
measured property. The approximation error is also called digitization error.
15. TRANSMITTER:
In industrial process control, a "transmitter" is any device which converts measurements
from a sensor into a signal to be received, usually sent via wires, by some display or
control device located a distance away.
C. PRESSURE MEASUREMENT:
I. INTRODUCTION
WHAT IS PRESSURE?
ATMOSPHERIC PRESSURE
HYDROSTATIC PRESSURE
MODES OF PRESSURE
II. PRESSURE SENSORS/TRANSDUCERS
BOURDON TUBE
SPRING AND PISTON
BELLOWS AND CAPSULES
DIAPHRAGM
III. ELECTRICAL PRESSURE TRANSDUCERS
PIEZO-RESISTIVE STRAIN GAUGE
CAPACITIVE
ELECTROMAGNETIC
OPTICAL
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 5
Information Sheet 3-2: Personal Protective Equipment
I. INTRODUCTION
Pressure is defined as a force per unit area, or is the force exerted by an object on a
certain area. Pressure results from molecules exerting a force by impacting over a
defined area. The relationship is given by:
Pressure (P) = Force (F)
Area (A)
Atmospheric pressure is the amount of pressure that a column of air exerts on a body
due to the influence of gravity.
Vacuum is a volume of space that is essentially empty of matter, such that its gaseous
pressure is much less than atmospheric pressure. Vacuum pressure is pressure lower
than atmospheric pressure.
Hydrostatic pressure is the amount of pressure that a column of liquid exerts on a body
due to the influence of gravity.
Pressure (P) =Specific Gravity (S.G.) * Height (H)
The objects of pressure measurements are gas, liquid, and steam.
Modes of pressure measurement:
\ Install (ICD) Date: Developed Date: Revised Page #
Instrumentation and Control Devices April 27, 2010 6
Code No.
ECL724301
Information Sheet 3-2: Personal Protective Equipment
II. MECHANICAL PRESSURE SENSOR/TRANSDUCER
Bellows
Bourdon Piston
III. ELECTRICAL PRESSURE TRANSDUCER
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 7
Information Sheet 3-2: Personal Protective Equipment
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 8
Information Sheet 3-2: Personal Protective Equipment
D. LEVEL MEASUREMENT:
I. Level Transducer Selection Checklist
Key questions to ask before selecting a level measurement transducer:
Are you measuring a liquid or solid?
What are the application's temperature and pressure ranges?
Is point level or continuous measurement required?
What level measurement range do you need?
Is the measured material electrically conductive?
Will the material coat or build up on surfaces?
Does turbulence, foam, or vapor occur at the surface of the liquid?
Will you need contact or non-contact level measurement?
What kind of output do you need–analog, relay, digital display, etc.?
II. Types of Level Transducer
Level measurement transducers fall into two main types:
Point level measurement type is used to mark a single discrete liquid height–a
preset level condition. Generally, this type of sensor functions as a high alarm,
signaling an overfill condition, or as a marker for a low alarm condition.
Continuous level measurement type is more sophisticated and can provide level
monitoring of an entire system. They measure fluid level within a range, rather than
at a one point, producing an analog output that directly correlates to the level in the
vessel.
III. Level Transducers
1. Point and continuous level detection for solids
1.1 Vibrating point
1.2 Rotating paddle
1.3 Admittance-type
2. Point level detection of liquids
2.1 Magnetic and mechanical float
2.2 Pneumatic
2.3 Conductive
3. Both for Point Level Detection and Continuous Monitoring of Solids and Liquids
3.1 Capacitance
3.2 Optical interface
3.3 Ultrasonic
3.4 Microwave
Code No. Install (ICD) Date: Developed Date: Revised Page #
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Information Sheet 3-2: Personal Protective Equipment
4. Continuous level measurement of liquids
4.1 Magneto-restrictive
4.2 Resistive chain
4.3 Hydrostatic pressure
4.4 Air bubbler
4.5 Gamma ray
Note: Refer to Module 1-1 power-point regarding the details of Level Transducers.
E. TEMPERATURE MEASUREMENT:
1. INTRODUCTION:
Temperature is the degree of hotness or coldness of a body measured on a
definite scale.
Temperature Scales:
Code No. Install (ICD) Date: Developed Date: Revised Page #
ECL724301 Instrumentation and Control Devices April 27, 2010 10
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