PROCESS INSTRUMENTATION
Piping & Instrumentation Diagram
Mrs Anis Atikah Ahmad
Email:[email protected] Tel: 04-976 3245
OUTLINE
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Introduction to P & ID
Introduction to Process Control
Instrumentation Symbology
Instrumentation Numbering
Process Control Variety
PFD
P&ID
1. Introduction to P & ID
 Also known as “PROCESS & INSTRUMENTATION DIAGRAM”
 Detailed graphical representation of a process (i.e piping,
equipment, and instrumentation) necessary to
design, construct and operate the facility.
 Common synonyms for P&IDs include Engineering Flow
Diagram (EFD), Utility Flow Diagram (UFD) and Mechanical
Flow Diagram (MFD).
1.1 Component of P & ID
1.All PFD components
2. Process Control Loop (if any)
3.All instruments (eg: transmitter, indicator, alarm)
4. Instrumentation Tagging & Numbering
2. Introduction to Process Control
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Component of Process Control
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Measuring device (Sensor & transmitter)
Controller
I/P Transducer (if FCE is control valve)
Final Control Element (Control Valve, Pump, Heater)
2. Introduction to Process Control
Basic Loop
Set point
Controller
Transmitter
Fluid
Fluid
Orifice
(Flow Sensor)
2. Introduction to Process Control
Basic Loop
Process
Sensing Element
Control
Valve/
Heater/
Pump
Final Control
Element
Measuring
Element
Transmit
Element
Control Element
Controller
Sensor
Transmitter
2.1 Sensor
SENSORS (Sensing Element)
 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.
 For example, a mercury thermometer converts the measured temperature into
expansion and contraction of a liquid which can be read on a calibrated glass tube.
A thermocouple converts temperature to an output voltage which can be read by
a voltmeter.
 For accuracy, all sensors need to be calibrated against known standards.
2.1.1 Temperature Sensor
Thermocouple
- Cheaper than RTD
- Durable
- React faster to
changes in
temperature
- Can measure a bigger
range of temperatures
2.1.1 Temperature Sensor
Resistance Temperature Detector (RTD)
- Readings are more
accurate and more
repeatable
- Expensive
2.1.2 Flow Sensor
Turbine Flow Meter
-Very accurate ( commonly used to prove other meters.)
-Not usable in dirty streams or with corrosive materials
2.1.2 Flow Sensor
Magnetic Flow Meter
- Flow rate unaffected by fluid density,
consistency, viscosity, turbulence, or piping
configuration.
- Highly accurate
- Corrosion-resistant using Teflon liner and
platinum electrodes
- Wide flow measuring ranges & no pressure
drop
- Costly, relative to other flow meter types.
- Cannot be used for gas flow measurements
2.1.2 Flow Sensor
Orifice Flow Meter
•Fabrication simple and inexpensive.
•No limitations on the materials of construction,
line size and flow rate
2.1.2 Flow Sensor
Venturi Meter
• Can be used for high/extreme temperature
• Highly expensive
• Larger and heavier to handle
• Can be used for gas & liquid
2.1.3 ASSIGNMENT
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Discuss the function of each temperature and flow sensor
in slide 11-16.
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Must include the discussion on how they operate (any principle
used)
Deadline: 24 November 2016
2.2 Transmitter
A transmitter measures the process variable and transmits the information to a
central location where the comparison takes place
Differential Pressure
Transmitter
Pressure Transmitter
2.3 Controller
Controller is a device which monitors and affects the operational conditions of a
given dynamical system.
The operational conditions are typically referred to as output variables of the system
which can be affected by adjusting certain input variables.
Indicating Controller
Recording Controller
2.4 I/P Transducer
A device that converts electric signal to pneumatic signal.
Control Valve
2.5 Final Control Element
Final Control Element is a device that directly controls the value of manipulated
variable of control loop.
Final control element may be control valves, pumps, heaters, etc.
Pump
Control Valve
Heater
2.6 Process Control Structure
Example 1
 Figure below shows the liquid vessel for boiler system. The control objective in this system is to
maintain the vessel temperature at 120 oC. The heater will be switched off when the temperature
reached the desired temperature. Draw feedback control loop for the system.
TC
What is the
final control
element in this
system?
-HEATER
Fluid in
V-100
TT
Fluid out
V 100
2.6 Process Control Structure
Exercise 1: Draw TWO control loops to
control level L3 and L5 at the
desired level.
LT 1
LIC 1
LCV-100 close when level reached
L3
LCV-100 open when level below L3
L3
L2
LCV-100
TK-100
L1
LT 2
LIC 2
L5
LCV-101 close when level reached
L5
LCV-101
V-100
LCV-101 open when level below L5
L4
2.6 Process Control Structure
Answer 2
LIC 1
LT 1
L3
L2
LCV-100
TK-100
LIC 1
LCV-100 close when level reached
L3
LT 1
LCV-100 open when level below L3
L1
LIC 2
L5
LCV-101
LT 2
V-100
L4
LT 2
LIC 2
LCV-101 close when level reached
L5
LCV-101 open when level below L5
3. Instrumentation Symbology
Instruments that are field mounted.
-Instruments that are mounted on process plant (i.e sensor that
mounted on pipeline or process equipments.
Field
mounted on
pipeline
3. Instrumentation Symbology
Instrumentation Symbology
Instruments that are board mounted
-Instruments that are mounted on control board.
3. Instrumentation Symbology
Instrumentation Symbology
Instruments that are board mounted (invisible).
-Instruments that are mounted behind a control panel board.
3. Instrumentation Symbology
Instruments that are functioned in Distributed Control System (DCS)
- A distributed control system (DCS) refers to a control system usually of
a manufacturing system, process or any kind of dynamic system, in which
the controller elements are not central in location (like the brain) but are
distributed throughout the system with each component sub-system
controlled by one or more controllers. The entire system of controllers is
connected by networks for communication and monitoring.
3. Instrumentation Symbology
3. Instrumentation Symbology
FC
Flow Controller
PT
FE
Flow Element (Orifice Plate/)
Pressure Transmitter
Venturi tube
FI
Flow Indicator
FT
Flow Transmitter
LC
Level Controller
FS
Flow Switch
LG
Level Gauge
FIC
Flow Indicating Controller
LR
Level Recorder
FCV
Flow Control Valve
LT
Level Transmitter
FRC
Flow Recording Controller
LS
LIC
Level Switch
Level Indicating Controller
PC
Pressure Controller
LCV
Level Control Valve
PG
Pressure Gauge
LRC
Level Recording Controller
PI
Pressure Indicator
PR
Pressure Recorder
3. Instrumentation Symbology
PS
Pressure Switch
TI
Temperature Indicator
PIC
Pressure Indicating Controller
TR
Temperature Recorder
PCV
Pressure Control Valve
TS
Temperature Switch
PRC
Pressure Recording Controller
TC
Temperature Controller
PDI
Pressure Differential Indicator
TT
Temperature Transmitter
PDR
Pressure Differential Recorder
PDS
Pressure Differential Switch
PDT
Pressure Differential Transmitter
3. Instrumentation Symbology
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Example
3.1 Signal Line Symbology
Signal Lines Symbology
4. Instrumentation Tagging & Numbering
 XYY CZZLL
X represents a process variable to be measured.
(T=temperature, F=flow, P=pressure, L=level)
YY represents type of instruments.
C designates the instruments area within the plant.
ZZ designates the process unit number.
LL designates the loop number.
4. Instrumentation Tagging & Numbering
 LIC 10003
L
= Level shall be measured.
IC
= Indicating controller.
100
= Process unit no. 100 in the area of no. 1
03
= Loop number 3
4. Instrumentation Tagging & Numbering
 FRC 82516
F
= Flow shall be measured.
RC
= Recording controller
825
= Process unit no. 825 in the area of no. 8.
16
= Loop number 16
Various type of process control strategies
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Feedback Control
Feedforward Control
Ratio Control
Cascade Control
Split Range Control
Feedback Control
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One of the simplest process control schemes.
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A feedback loop measures a process variable and sends the measurement to a
controller for comparison to set point. If the process variable is not at set point,
control action is taken to return the process variable to set point.
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Advantage: corrective action occurs as soon the CV deviates from setpoint.
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Disadvantage: not provide predictive control action to compensate for the effects of
known or measurable disturbance
Parameter being
measured:
Controlled
Variable ( level of
the water in the
boiler)
Feedforward Control
Basic concept: to measure important disturbance variables and take corrective
action before they upset the process.
Parameter being
measured:
disturbance
variable (steam
flow rate)
Feedforward Control (cont.)
Feedforward control is normally used in combination with feedback controller.
Controller with
summing functions
are used in these
combined systems
to sum up the
input from both
the feedforward
loop and the
feedback loop, and
send a unified
signal to the final
control element.
Feedforward plus feedback controller
Ratio Control
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Ratio control is used to ensure that two or more flows are kept at
the same ratio even if the flows are changing.
FIC
FF
FT
FT
Water
Acid
2 part of water
1 part of acid
Cascade control
 Cascade Control uses the output of the primary controller (master) to manipulate the set
point of the secondary controller (slave) as if it were the final control element.
- Used when the disturbances are
associated with manipulated variable.
Split Range Control
Output of a controller is split to two or more control valves.
CV-102
pHIC
TK-102
(base feed tank)
pHT 1
TK-100
(pH adjustment tank)
CV-101
TK-101
(acid feed tank)
The diagram shows pH
adjustment; part of waste
water treatment process.
The process shall be
maintained at pH 6. When
the process liquid states
below pH 6, CV-102 will be
opened to dosing NaOH to
the tank TK-100. When the
process liquid states above
pH 6, CV-101 will be
operated to dosing HCl.
Exercise…
Identify type of control loop used below.
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PIC
Y
PT
FC
FT
V-100
Process variable need to be
controlled = Pressure