Study of Instrumentation Symbols as Per ISA Standards

INDUSTRIAL PROCESS CONTROL:STANDARDS

Purpose

To establish a uniform mean of designating instruments and instrumentation systems used for measurement and control.

Scope

1) General The procedural needs of various users

are different. The standard recognizes these needs, when they are consistent with the objectives of the standardly by providing alternative symbolism methods.

A number of examples are provided for adding information or simplifying the symbolism as desired.

Scope

2) Application to Industries Chemical. Petroleum. Power generation. Air conditioning. Metal refining.

Scope

3) Application to Work Activities Design sketches. Teaching examples. Technical papers, literatures, and discussions. Instrumentation system diagrams, loop diagrams, logic

diagrams. Functional descriptions. Flow diagrams:

Process. Mechanical. Engineering. Systems piping (process) and instrumentation.

Construction drawings. Specifications, purchase orders, manifests, and other

lists.

Identification of the System

Each instrument may be represented on diagrams by symbols.

Instrument or function to be identified is designated by an alphanumeric code or tag number.

The symbols may be accompanied by a tag number.

FV101

Identification of the System(Tag Number)

Instrument Identification or tag number

TIC103


Loop identification

TIC103


Loop numberFirst number is used to identify the loop.The succeeding numbers is the serial number of the instrument in a particular loop.

TIC103


Function IdentificationFunction of the instrument is identified.

TIC103


First letterIdentifying the measured or initiating variable.

May have a modifier is intended to represent a new and separate measured variable.

TIC103


Succeeding lettersIdentifying the function performed.Second letter is used for the readout or passive function.Third letter is used for the output function.The succeeding letters may have a modifier to identify a separate function.

TIC103

Function Identification

First Letter Succeeding Letter

Measured or Initiating Variable

Modifier Read out or Passive Function

Output Function

Modifier

A Analysis Alarm

B Burner User’s choice

User’s choice

User’s choice

C User’s choice

Control

D User’s choice

Differential

E Voltage Sensor

F Flow rate Ratio

G User’s choice

Glass

H Hand High

I Current Indicator

J Power Scan

K Time Time rate Control station

L Level Light Low

M User’s choice

Momentary Middle

First Letter Succeeding Letter

Measured or Initiating Variable

Modifier Read out or Passive Function

Output Function

Modifier

N User’s choice

User’s choice

User’s choice

User’s choice

O User’s choice

Orifice

P Pressure Point

Q Quantity Integrate

R Radiation Record

S Speed Safety Switch

T Temperature

Transmit

U Multivariable

Multifunction

Multifunction

Multifunction

V Vibration Valve, damper

W Weight, Force

Well

X Un classified

X axis Un classified

Un classified

Un classified

Y Event, state

Y axis Compute

Z Position Z axis Actuator

Symbols

The symbols are intended to depict instrumentation on diagram and drawing.

Instrument Line Symbols

Instrument supply or connection to process

AS

Air supply

IA

Instrument Air

PA

Plant Air

ES

Electric Supply

GS

Gas Supply

HS

Hydraulic Supply

NS

Nitrogen Supply

SS

Steam Supply

WS

Water Supply The supply level may be added to the instrument supply line.E.g:- AS-100; ES-24DC

Undefined Signals

Pneumatic signal

Electric Signal

Hydraulic Signal

Capillary Tube

Internal system link (s/w or data link)Mechanical link

Electric binary Signal

General Instrument or Function Symbols

Discrete Instruments

Shared Display

Computer Function

Primary Location Normally

Accessible to Operator

Field Mounted

Auxiliary Location Normally


Programmable Logic Control

Symbol Size may vary according to the user’s needs and the type of document.

Abbreviations of the user’s choice such as IP1 (Instrument Panel 1), IC2

(Instrument Console 2), CC3 (Computer Console 3), etc. may be used when it is

necessary to specify instrument or function location.

IP1



Shared Display

Computer Function



Field Mounted






Shared Display

Computer Function



Field Mounted




Normally in accessible, or

behind-the-panel devices or

functions may be depicted by

using the same symbol but with

dashed horizontal bars.



Shared Display

Computer Function

Primary Location Normally In-accessible to

Operator

Field Mounted

Auxiliary Location Normally In-accessible to

Operator


Control Valve Body Symbols

General Symbol

Angle

Butterfly

Rotary Valve

Three Way Valve

Four Way Valve

Globe Valve

Diaphragm Valve

Actuator Symbols

Diaphragm, spring opposed or unspecified actuator

Diaphragm pressure balanced

M Rotary motor (shown typically with electric signal may be hydraulic or pneumatic)

Actuator Symbols

Digital

Spring opposed single acting

Double acting

D

Actuator Symbols

Solenoid

Electrohydraulic

Valve actuator with attached electro pneumatic converter

S

E/H

TY

I/P

Actuator Symbols

For pressure relief or safety valve only

Hand actuator or hand wheel

Symbols for Self Actuated Regulators, Valves and Other Devices

FICV

Automatic regulator with integral flow indication

FI

Indicating variable area meter with integral manual throttle valve

Upstream alternative

Downstream alternative

FO

Restriction orifice (orifice plate, capillary tube, or multistage type, etc.) in process line


Restriction orifice drilled in valve (instrument tag number may be omitted if valve is otherwise identified

Flow slight glass, plain or with paddle wheel, flapper etc.

FO

Flow straightening vane (use of tag number is optional. The loop number may be the same as that of the associated primary element)

FG

FX


Hand control valve in process line

HS002

Hand actuated on-off switching valve in pneumatic signal line

HV

Level regulator with mechanical linkage

TankLCV


Pressure reducing regulator, self contained with hand wheel adjustable set point

Pressure reducing regulator with external pressure tap

PCV

Differential pressure reducing regulator with internal and external pressure taps

PCV

PDC


Back pressure regulator, self contained

Back pressure regulator with external pressure trap

PCV

Pressure reducing regulator with internal outlet pressure relief valve, and optional pressure indicator

PCV

PDC


Pressure relief or safety valve, general symbol

Pressure relief or safety valve, straight through pattern, spring or weight loaded, or with internal pilot

PCV

Vacuum relief valve, general symbolPCV


Pressure and vacuum relief valve, spring or weight loaded, or with internal pilot

PCV

Vacuum Pressure

Symbols for Actuator Action in Events of Actuator Power Failure

Two way valve, fail open

Two way valve, fail closed

A B

C

Three way valve, fail open to path AC

Symbols for Actuator Action in Events of Actuator Power Failure

Four way valve, fail open to paths CB and DA

Any valve, fail locked (position does not change)

Any valve, fail indeterminate

A B

C

D

Primary Element Symbols

AIT001

AIT002

Dual analysis indicating

BE001

BI002

One burner ultra-violet flame detector connected to analog type flame intensity indicator


BE001

BE002 Two burner flame rod

sensor connected to common switch

BTBG003

Television camera and receiver to view burner flame

BS003

S TV


Orifice plate with flange or corner taps connected to differential pressure type flow indicator

Orifice plate with vena contracta taps

VC

FI005

FE002


Orifice plate with vena contracta, radius, or pipe taps connected to differential pressure type flow transmitter

Venturi tube

FT008


Variable area flow indicator

Flow element with connection for controller

FI017

FE017

FC018


Flow element integral with transmitter

Vortex sensor

FT017

FE005


Flow nozzle

Indicating wattmeter connected to pump motorJI

001

FE029


KI001

Clock

KC TIC

Time schedule controller, analog type, or self contained function generator


VI001

Mechanical analysis in three planesVXT

002VYT003

VXI004

VYI005

VZT007

VZI008

VI006


Self contained on-off room thermostat actuating circulating pump motor

Cascade control: flow controller set by level control

JI001

1-0

LC104

FC100

FT

SP


Differential temperature indicator

Flow ratio controller with two pens to record flow

FT101

TT101

TT102

TDI103

FT102

FR104

FR105

FFC103


Flow ratio controller with one pen to record flow ratio

Mass flow computation performed by mass-flow computing relay ‘FY’ having linear inputs for pressure and temperature and a non-linear input for flow

FFC103

FT101

FT101

TT117

FIC111

FY

PT201

FT101

GS

MassFlow


Flow transmitter with external temperature compensatorTT

300

FYFT

400

TRC302

Pressure balanced valve


TSL301

PSH501

FIC404

M

TSL301

PSH501

FIC404

MFY

Flow control loop that may be blocked by interlock actuated by either low temperature or high pressure

Heat Transfer Elements

Water cooled exchanger

Water cooled condenser

Shell and tube exchanger

Pumps and Compressors

Centrifugal Reciprocating

Rotary Blower or fan

Process Pressure Vessels

or Horizontal drums

or Vertical drums

Thank You

Study of Instrumentation Symbols as Per ISA Standards

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