1. PROCESS MODELLING
• Instrumentation Symbols,
Table 2: ANSI/ISA-S5.1-1984 Instrumentation Symbols and Identification
|
LETTER
|
FIRST LETTER
|
SECOND LETTER
|
|
A
|
Analysis
|
Alarm
|
|
B
|
Burner, Combustion
|
User’s Choice
|
|
C
|
User’s Choice
|
Control
|
|
D
|
User’s Choice
|
|
|
E
|
Voltage
|
Sensor (Primary Element)
|
|
F
|
Flow Rate
|
|
|
G
|
User’s Choice
|
Glass (Sight Tube)
|
|
H
|
Hand (Manually Initiated)
|
|
|
I
|
Current (Electric)
|
Indicate
|
|
J
|
Power
|
|
|
K
|
Time or Time Schedule
|
Control Station
|
|
L
|
Level
|
Light (pilot)
|
|
M
|
User’s Choice
|
|
|
N
|
User’s Choice
|
User’s Choice
|
|
O
|
User’s Choice
|
Orifice, Restriction
|
|
P
|
Pressure, Vacuum
|
Point (Test Connection)
|
|
Q
|
Quantity
|
|
|
R
|
Radiation
|
Record or Print
|
|
S
|
Speed or Frequency
|
Switch
|
|
T
|
Temperature
|
Transmit
|
|
U
|
Multivariable
|
Multifunction
|
|
V
|
Vibration, Mechanical Analysis
|
Valve, Damper, Louver
|
|
W
|
Weight, Force
|
Well
|
|
X
|
Unclassified
|
Unclassified
|
|
Y
|
Event, State or Presence
|
Relay, Compute
|
|
Z
|
Position, Dimen sion
|
Driver, Actuator, Unclassified
|
• Line symbols include,
• Sensor and actuator symbols include,
• An example of a process diagram is given below,
