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