General information
14
Optional
Primary
location
Field
mounted
Discrete
instruments
Shared display
Shared control
Computer
function
Programmable
logic control
Pilot
Light
R
I
Interlock
logic
Reset for
latch-type
actuator
Instruments
supply or
connection to
process
Pneumatic
signal
Electric
signal
I -
0
M
ON - OFF
Analog
output
variable
Limit of
supply
Identification letters
( ISA Symbols )
First letter
Measured or
initialing variable
Modifier
Readout or
passive function
Output
function
Modifier
Succeeding letters
H
A
B
C
D
E
F
G
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Analysis
Alarm
Burner
Combustion
User's choice User's choice User's choice
User's choice
User's choice
User's choice
User's choice
User's choice
User's choice
User's choice User's choice
User's choice
Control
Differential
Voltage
Sensor
(Primary
element)
Flow rate
Ratio
(Fraction)
Glass
Viewing device
Hand
High
Current
(Electrical)
Indicate
Power
Scan
Time
Time schedule
Time rate
of change
Control
station
Level
Light
Low
Orifice
Restriction
Pressure
Vacuum
Point (Test)
Connection
Quantity
Integrate
Totalize
Radiation
Record
Momentary
Middle
Intermediate
Speed
Frequency
Safety
Switch
Temperature
Transmit
Multivariable
Multifunction
Multifunction
Multifunction
Vibration
Mechanical
analysis
Valve, Damper
Louver
Weight
Force
Well
Unclassified
Unclassified
Unclassified
Unclassified
X Axis
Event, State or
Presence
Y Axis
Z Axis
Relay, Compute,
Convert
Position
Dimension
Driver, Actuator
Final control
element
- Conductivity -
