Basic Instrumentation Symbols | P&ID | PFD | Gaurav Singh Rajput

1. Instrumentation
Symbols (P&ID)

2. TYPES OF P & IDs
 PFD (Process Flow Diagram)
 MFD (Metallurgical Flow Diagram)
 P&ID (Piping & Instrument Diagram)
 P&ID Legend
(Drawing which
detail
symbols used)
 UFD (Utility Flow Diagram)
 AFD (Auxiliary Flow Diagram)

3. P & ID DEFINITION
 P&ID is a detailed graphical
representation of a process
the hardware and software
including
necessary to design, construct and
operate the facility.
- Process Industry Practices (PIP)

4. P & ID Requirements
 Process Flow Diagram
 Project Statement
 Process Data Sheet
(PFD)
 Temperature and Pressure Diagram

5. Process Flow Diagram

7. A P&ID is:
 Language of Symbols
 Schematic of Process
 Displays Relative
Orientation/Configuration/Function
 Communication Tool
 Graphical Table of Contents

8. A P&ID is not:
 Piping Isometric
 Equipment Fabrication
 Scale Drawing
 Control Logic Diagram
Diagram
 Something to Convey Process
Information

9. P & ID
CONTAINS DETAILED INFORMATION
 Process & Utility Streams
 All Process Equipment
 Complete Instrumentation
 Analog & Digital Control

10. P&ID LEGEND
 Symbols and Tagging Information
 Instrument Signal Types
 Relay Functions
 Logic Symbols
 Valve Body and Actuator
 Abbreviations
Symbols
 Miscellaneous Symbols and Information

11. P & ID LEGEND
Instrument Symbols Design Basis
 ISA S5.1 Instrumentation Symbols and
Identification
 Defines:
 Instrument Symbols
 Tagging Conventions
 Loop Identification
 Provides Examples
 ISA S5.3DCS Symbols
 Client Requirements

12. Instrument Symbols Design Basis
The Instrumentation, Systems, and Automation
Society (ISA) is one of the leading process
control trade and standards organizations. The
ISA has developed a set of symbols for use in
engineering drawings and designs of control
loops (ISA S5.1 instrumentation symbol
specification).

13. P&ID LEGEND
 How to read P&ID

14. P & ID LEGEND

15. P & ID LEGEND

16. BALLOONS
The balloon or bubble symbol - this
represents an instrumentation and
control device.
The size is 5/16” or 10 mm in diameter
General guideline: the text inside must be
readable

17. According to ISA:
Local: The location of an instrument that is neither in nor on a
panel or console, nor is it mounted in a control room. Local
instruments are commonly in the vicinity of a primary element or
a final control element. The word "field" is often used
synonymously with local.
Local panel: A panel that is not a central or main panel. Local
panels are commonly in the vicinity of plant subsystems
sub-areas. The term "local panel instrument" should not
confused with "local instrument."
or
be
Panel-mounted: A term applied to an instrument that
mounted on a panel or console and is accessible for an
is
operator's normal use. A function that is normally accessible
to an operator in a shared-display system is the equivalent of
a discrete panel-mounted device.

18. BALLOONS
Types of balloon
symbols:

19. BALLOONS
In a P&ID, a circle represents individual measurement instruments,
such as transmitters, sensors, and detectors
• Single horizontal line indicates that the instrument or function is
located in a primary location (e.g., a control room).
• Double horizontal line indicates that the function is in an auxiliary
location
• Absence of the line indicates that the function is field mounted
• Dotted line indicates that the function or instrument is
inaccessible

20. A square with a circle inside represents instruments that both
display measurement readings and perform some control
function.
A hexagon represents computer functions, such as those
carried out by a controller

21. A square with a diamond inside represents
PLCs.
Directional arrows showing the flow direction
represent a pump.

22. P&ID LEGEND
Mounte
d
Mounted
Instrument
Room
Mounted XX
X
Mounte
d
Interlock
Logic
xxx
xxx
INSTRUMEN
T
BALOONS
xx
xxx
Local
Mounted
Discrete
Instrument
XX
XXX
Control
Room
Discrete
Instrument
xx
xxx
xx
Control
Room
Mounte
d
DCS Function-
Shared Display /
Control with
Auxilliary Operator
Interphase Device
xx
xxx
Control Room
Mounted Discrete
Instrument Operator
Inaccessable or Back
of Panel
xx
xxx
Local Panel
Mounted
Discrete
Instrument
xx
Control Room
with Shared
Control
Operator
Inacessable
xx
xxx
Control Room
Mounted
Instrument with
Shared Display
And Shared
Control
XX
XXX
Main Control
Room Mounted
Computer
Function
XX
XXX
Secondary
Control
Computer
Function
XX
XX
X
XX
Control
Room
Mounte
d
DCS Logic
Function- Shared
Display / Control
with Auxilliary
XX
XXX
Control Room
Mounted
Programable
Logic Control
XX
XXX
Local Panel
Mounted
Programmable
Logic Control
I
Control
Room
Distributed
Control

23. The Tag Symbol
This represents a unique
identification.
name given as an
Example: PIC-069
Where it is placed:
- inside the balloon
Example:
PIC
symbol
069

24. P & ID LEGEND - INSTRUMENT TAGGING
TYPICAL TAGGING CONVENTION
42FT-371A
FT
37
1
42 FT 371 A
SUFFIX (IF REQUIRED)
LOOP NUMBER
INSTRUMENT TYPE
UNIT IDENTIFIER

25. Example:
Number
3 6 T I C 6 7 3 A
This describes
a TemperatureIndicatin
g
Controller, belonging to
Loop
Plant ). The suffix ‘A’ if used,
No. 673 located at Plant No. 36
( Power
means this controller receives signal from two separate
Temperature
Transmitters. One of them would be tagged as 36 TIC 673A
and the other would be 36 TIC 673B.
Temperature
Indicating
Controller
Controller receives from
Temperature Transmitter ‘A’
Power Plant
Loop
Number

26. P & ID LEGEND - INSTRUMENT
TAGGING
Instrument identification system, generally
include
th
e
following
:
1. Tag number
s
to defin
e
proces
s
functio
n,
loo
p
number and plant
number.
2. Symb
ol
to
identify
pneumati
c,
electrica
l,
capillar
y,
control
hydrauli
c,
signals.
Symbol
s
Device
s
soni
c
or radioactivi
ty
proces
s
3. to represe
nt
primar
y
flow,
an
d
Fina
l
Contro
l
tha
t
gover
n
level
,
pressur
e,
temperature and other process variables, i.e.
pH, CO,
etc.
Following is a table showing the functional
meanings of
identification letters as designated by the Instrument
Society of America ( ISA Recommended Practice RP
5.1 )

27. P & ID
LEGEND –
Instrument
Identification
Letters

28. P & ID LEGEND – Instrument
Letters
Identification
Divert
B – Flame
C – Typically Conductivity – Electrical
D – Typically Density or Specific Gravity

29. P & ID LEGEND – Instrument Identification
Letters (continuation…)

30. P & ID LEGEND - INSTRUMENT TAGGING
ISA-S5.1 INSTRUMENT
FIRST LETTER
IDENTIFICATION
SUCCEEDING LETTERS
 F FLOW  A ALARM
 L LEVEL E ELEMENT

 P PRESSURE I INDICATE

 T TEMPERATURE S SWITCH

 H HAND T TRANSMITTER

 S SPEED V VALVE

 V VIBRATION

31. First Letter Code
In general, the process that is to be
monitored by the instrument is indicated by
the first
F
L
P
T
letter
=
=
=
=
of the coding,
Flow
Level
Pressure
for example:
Temperature

32. Second Letter Code
The second letter in the coding indicates the
function of
FI
FC
LA
LR
PT
TE
the
=
=
=
=
=
=
instrument, for example:
Flow Indicator
Flow Controller
Level Alarm
Level Recorder
Pressure Transmitter
Temperature
EIement

33. Optional Third Letter Code
In some cases, when the instrument is used for two
purposes or when the function of the instrument
has to be more
used,
for example:
clearly specified, a third letter is
FIC
LAH
LAL
=
=
=
Flow Indicating Controller
Level Alarm High
Level Alarm Low

34. Example:
Succeeding-Letter

35. LOOP
a combination of two or more
instruments or control function
arranged so that signals pass from
one to another for the purpose of
measurement and/or control of a
process variable.

36. TYPICAL LOOP: Actual
Setpoint

37. TYPICAL LOOP: P & ID
Typical Flow Loop with Separate I/P
Shown on P&ID Implied

38. Pressure Control Loop

39. Flow Control Loop

40. Level Control Loop

41. Temperature Control Loop

42. Field or Locally Mounted Symbol
A circle
field or
with lettered code only represents a
locally mounted instrument.
PSV

43. Field or Locally Mounted Symbol
A circle
field or
with lettered code only represents a
locally mounted instrument.
PSV

44. Field or Locally Mounted Symbol
PIT
PT

45. Field or Locally Mounted Symbol
PIT
PT

46. Field or Locally Mounted Symbol
PIT

47. Field or Locally Mounted Symbol
PIT

48. Field or Locally Mounted Symbol
FIT

49. Field or Locally Mounted Symbol
FIT

50. Field or Locally Mounted Symbol
FIT

51. Field or Locally Mounted Symbol
FIT

52. Field or Locally Mounted Symbol
LT

53. Field or Locally Mounted Symbol
LT

54. Field or Locally Mounted Symbol
LIT

55. Field or Locally Mounted Symbol
LIT

56. Field or Locally Mounted Symbol
Instrument Stanchion (Wall Mounted)

57. Field or Locally Mounted Symbol
Instrument Stanchion

58. Field or Locally Mounted Symbol
Transmitters

59. Field or Locally Mounted Symbol
Control Valve

60. Field or Locally Mounted Symbol
Relief Valve

61. Local Panel Mounted
PI

62. Local Panel Mounted
PI

63. Local Panel Mounted
Local Gauge Rack

64. Local Panel Mounted
Local Panel

65. Local Panel Mounted
Analyzer Sampling System

66. Control Room Panel Mounted
A circle with a solid line across its diameter and the
lettered code above this line indicates
room panel mounted instrument.
a control
LR

67. Control Room Panel Mounted
A circle with a solid line across its diameter and the
lettered code above this line indicates
room panel mounted instrument.
a control
LR

68. Control Room Panel Mounted
TR

69. Control Room Panel Mounted
TR

70. Control Room Rack Mounted
A circle with a dotted line across its diameter
indicates a control equipment room rack,
usually behind the control panel), mounted
instrument
(i.e.
LAH

71. Panels

72. Panels

73. Distributed Control Symbol
Video Display or
Monitor, visible at
console, accessible
to operator
Video Display or
Monitor, not visible
at console, not
accessible to
operator

74. Distributed Control Symbol

75. Distributed Control System - Console

76. Consoles

77. P & ID LEGEND: Instrument Line Symbols
 Represent:
 Instrument and device connections to
process measurement point.
 Connection to Instrument power
supply
 Signals between measurement and
control instruments and functions

78. Instrument Line Symbols

79. Instrument Line Symbols

80. Instrument Line Symbols

81. P&ID LEGEND: INSTRUMENT SYMBOLS
ORIFICE CONTROL VALVE (UNDEFINED)
VORTEX DIAPHRAGM
VENTURI
MOTOR OPERATED
ROTAMETER (OR PURGE)
(SHOWN WITH OPTIONAL
INTEGRAL VALVE)
TYPICAL CONTROL VALVE
WITH POSITIONER AND
SOLENOID
PRESSURE RELIEF
OR SAFETY VALVE
PRESSURE REDUCING
REGULATOR
(SELF-CONTAINED)

82. P&ID LEGEND: INSTRUMENT SYMBOLS

83. Valve Body Symbols

84. Valve Actuator Symbols

85. P&ID LEGEND: INSTRUMENT SYMBOLS

86. P&ID LEGEND: INSTRUMENT SYMBOLS

87. IN-LINE INSTRUMENTS
Inline Instruments
connection size
 Control Valves
are detailed with type and
 Relief Valves

88. IN-LINE INSTRUMENTS
 Flow Elements/Meters
 Emergency Shutdown Valves

89. Function Symbol

90. Function Symbol

91. Process Equipment Symbol
This represents a special or unique symbol given
to a process equipment, such as vessels, tanks,
drums, heaters or exchangers, pumps, mixers
and agitators, fans, compressors, etc. These
symbols are common with the mechanical and
chemical engineering field.

92. Process Equipment Symbol

93. Process Equipment Symbol

94. Process Equipment Symbol

95. Process Equipment Symbol

96. Process Equipment Symbol

97. Process Equipment

98. Process Equipment

99. Process Equipment
Dehydrator

102. P & ID EXAMPLE

103. TYPICAL LOOP
Typical Temperature Loop with Valve
Positioner
Implied
Shown on P&ID

104. TYPICAL LOOP
Typical Flow Loop with Separate I/P
Shown on P&ID Implied

105. TYPICAL LOOP
Typical Valve Detail
Implied
Shown on P&ID

106. P & ID EXAMPLE – Control Valve

107. P & ID EXAMPLE

108. P & ID EXAMPLE

109. P & ID EXAMPLE – Level Control

110. P & ID EXAMPLE – Level Control
(Electrical Traced)

111. P & ID EXAMPLE – Motorized Valve

112. P & ID EXAMPLE-Motor Control 1

113. P & ID EXAMPLE - Motor Control 2

114. P & ID EXAMPLE – Motor Control 3

115. P & ID REVIEW
 Symbology
 Consistency of Control Depiction
 Applicability of Measurement & Control
Methods
 Correct Instrument Types
 System Operability

116. UFD EXAMPLE

117. AFD EXAMPLE

118. AFD EXAMPLE

119. AFD EXAMPLE