CHAPTER 1: INSTRUMENTATION EQUIPMENT

CHAPTER 1: INSTRUMENTATION EQUIPMENT
InstrumentatIon & Control
Chula/ongkom UnIversity
Chapter1: INSTRUMENTATION E" JMENT
Module 2: ISA Symbols
CHAPTER 1: INSTRUMENTATION EQUIPMENT
MODULE 2: ISA Symbols
MODULE OBJECTIVES:
At the end of this module, you will be able to:
1.
Sketch the symbols representing three different Idnds (pneumatic, electronic and mechanical) of
transmission line.
2.
State the instrument which a given standard ISA symbol represents, with respect to its function and
mounting location.
3.
Sketch a simple flows sheet using standard ISA symbols, given the function and location of different
instruments and the type of transmission line connecting them.
page1-2·1
Instrumentation & Control
Chulalongkorn University
Chapter 1: INSTRUMENTATION EQuiPMENT
Module 2: ISA Symrols
Introduction
•
Instruments on drawings which show the location and function of different devices are represented by
standard symbols.
•
most or Norm AmeriCa, a convention Dasea on
adopted.
I
• • ...
In
4'.·
....._
. ' 1 . . _ ..
I I .
I~A llnstrument ~oclety or AmeriCa} symDOIs nas Deen
r
_
Line Symbols
•
Transmission lines which link different instruments are shown in Figure 1.
MECHANICAL LINKAGE
---------
ELECfRICAL SIGNAL
-tI----HI-------IHf--
PNEUMATIC SIGNAL
-L
HYDRAtJLIC LINE
I::-
L
Figure 1 Symbols for Transmission Lines
Figure 1: Symbols for Transmission Lines.
page1·2·2
•
\
•
Chapter 1: INSTRUMENTA TION E",,,/PMENT
Module 2: /SA Symbols
Instrumentation & Control
Chulalongkom University
Instrument Symbols
•
Instruments are identified by circles with lettered codes (two or three letters) inserted. This lettered
code shows the instrument type and function.
The first letter in the Code
indicates the Process Parameter
monitored by the instrument
F= flow
L= Level
P= Pressure
T= Temperature
•
The second letter in the code
indicates the function of the
instrument
Fl = Flow Indicator
FC = Flow Controller
LA = Level Alarm
LR = Level Recorder
PT = Pressure -Transmitter
TE = Temperature Element
A third letter in the code is used when
the instrument has two functions;
it indicates the second function
FIC = Flow Indicating Controller
LAH = Level Alarm High
LAL = Level Alarm Low
To distinguish control room mounted instruments from local or field mounted instruments, a horizontal
line across the diameter of the circle is used.
e~
Control Room
Rack Mounted
High Level Alann
Control Room
Panel Mounted
Level Recorder
Field (orlocally)
Mounted Level Indicator
Figure 2: ISA Symbols and the Instruments they Represent.
page1·2·3
Chapter 1: INSTRUMENTATION Ec..<lIPMENT
Module 2: ISA Symbols
Instrumentation & Control
Chulalongkom University
Examplg
A level loop consists of:
Solution: ISA Symbols Representation of a level Loop
Field Mounted: Level transmitter
Level indicator
HIGH LEVEL ALARM
RACK MOUNTED
r
Control Room Panel Mounted:
Level controller
Level recorder
High level alarm
Low level alarm
I
Il __
r
I--.......;~ LOW
LEVEL ALARM
RACK MOUNTED
I
The level transmitter is connected
directly to the tank'and the rest of the
instruments are driven by the level
transmitter and used to monitor and
indicate the level in a tank.
Assuming that the signal transmitted is
electronic, draw a representative flow
sheet using ISA symbols.
"""--1
I
~
LEVEL TRANSMITTER
I
I
l - - f - - - 1 LEVEL
RECORDER
FRONT PANEL
LEVEL INDICATOR
MOUNTED
Field
page1-2-4
LEVEL CONTROLLER
-l-----l
FRONT PANEL
MOUNTED
Control Room
Chapter 1: INSTRUMENTATION Ec.._ .PMENT
Module 2: ISA Symbols
Instrumentation & Control
Chulalongkom UnIversity
Table 1
Instrument Identification Code
FIRST LETTER
Measured Variable
A
C
E
F
G
H
I
L
M
P
R
S
T
V
W
X
Y
Z
CURRENT
SUCCEEDING LETTERS
Output Function
Read-out or Passive
Function
,
ALARM
CONTROL
ELEMENT
I
I
Modifier
AVERAGE
CONTACT
FLOW RATE
GLASS
HAND (MANUAL)
HIGH
INDICATE
LEVEL
MOTORIZED
PRESSURE
NEUTRON FLUX
RECORD
SOLENOID
TEMPERATURE
MEDIAN
RELAY
SWITCH
TRANSMIT
VALVE
WELL
TRANSDUCER
COMPUTE
POSITION
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