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5 Graphic symbol tables
5.1 Graphic symbol tables
5.1.1 This clause provides in tabular form the graphic building blocks that are used to construct
diagrams for measurement and control loops, instruments, and functions in a concise, easily referenced
manner.
5.1.2 The graphic symbol sets included in this clause are intended to be used to prepare:
a) Instrumentation diagrams.
b) Functional diagrams.
c) Binary logic diagrams.
d) Electrical schematics.
5.1.3 The graphic symbols shown in the tables are drawn full size for use in full size sketches or
drawings.
5.1.4 The device and function symbols shown in Table 5.1.1 are based on the traditional 7/16-inch or
11mm circle format but may be changed to the often-used 1/2-inch or 12mm circle format.
5.1.5 Consideration shall be given to the size of reduced P&IDs when selecting symbol sizing.
5.1.6 All symbols shall maintain the size ratios shown in the tables when reduced or increased in size.
5.2 Tables to be used for common applications
5.2.1 Instrumentation diagrams that represent instrumentation devices and functions shall be
constructed from the symbols shown in:
a) Tables 5.1.1 and 5.1.2 — Measurement and control devices or functions.
b) Tables 5.2.1, 5.2.2, 5.2.3, and 5.2.4 — Measurement elements and transmitters.
c) Tables 5.3.1 and 5.3.2 — Lines, instrument to process or instrument to instrument.
d) Tables 5.4.1, 5.4.2, 5.4.3, and 5.4.4 — Final control elements.
e) Table 5.6 — Signal processing function blocks.
5.2.2 Functional diagrams that represent monitoring and control loops shall be constructed from the
symbols shown in:
a) Table 5.5 — Functional diagramming symbols.
b) Table 5.6 — Signal processing function block symbols.
c) Table 5.7 — Binary logic symbols.
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5.2.3 Binary logic diagrams that represent logic processes shall be constructed from the symbols
shown in:
a) Table 5.1.1 — Measurement and control devices or functions.
b) Table 5.7 — Binary logic symbols.
5.2.4 Electrical schematics that represent electrical circuits shall be constructed from the symbols
shown in:
a) Table 5.1.1 — Measurement and control devices or functions.
b) Table 5.8 — Electrical schematic symbols.
5.2.5 Symbols may be developed to show devices and functions not covered by this standard or to
simplify the depiction of frequently used instrumentation. Such uses shall be fully detailed by sketches or
notes on the drawing legend and detail sheets.
5.2.6 If new or revised symbols are developed they should be submitted to the ISA-5.1 committee for
inclusion in the next revision of this standard.
5.3 Graphic symbol table explanatory notes
The following notes, indicated in Tables 5.1 through 5.8 by parentheses, shall be used as an aid in
understanding the meanings of the symbols.
5.3.1 Tables 5.1.1 and 5.1.2 — Instrumentation device and function symbols:
(1) Devices and functions that are represented by these bubble symbols are:
(a) Used in shared display, shared control, configurable, microprocessor-based, and data-
linked instrumentation where the functions are accessible by the operator via a shared display or
monitor.
(b) Configured in control systems that include, but are not limited to, distributed control
systems (DCS), programmable logic controllers (PLC), personal computers (PC), and intelligent
transmitters and valve positioners.
(2) The user shall select and document one of the following for use of these symbols in a:
(a) Primary shared-display, shared-control system.
(b) Basic Process Control System (BPCS).
(3) The user shall select and document one of the following for use of these symbols in an:
(a) Alternate shared-display, shared-control system.
(b) Safety Instrumented System (SIS).
(4) Devices and functions represented by these bubble symbols are configured in computer systems
that include, but are not limited to:
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(c) Affected by controller or switch actions.
(2) Arrows shall be used if needed to clarify direction of signal flow.
(3) Users engineering and design standards, practices and/or guidelines shall document which
symbol has been selected.
(4) The line symbols connect devices and functions that are integral parts of dedicated systems,
such as distributed control systems (DCS), programmable logic controllers (PLC), personal computer
systems (PC), and computer control systems (CCS) over a dedicated communication link.
(5) The line symbols connect independent microprocessor-based and computer-based systems to
each other over a dedicated communications link, using but not limited to the RS232 protocol.
(6) The line symbols connect “intelligent” devices, such as microprocessor-based transmitters and
control valve positioners that contain control functionality, to other such devices and to the
instrumentation system, using but not limited to Ethernet fieldbus protocols.
(7) The line symbols connect “smart” devices, such as transmitters, to instrumentation system input
signal terminals and provide a superimposed digital signal that is used for instrument diagnostics and
calibration.
5.3.4 Tables 5.4.1, 5.4.2, 5.4.3 and 5.4.4 — Final control element symbols:
(1) Users engineering and design standards, practices, and/or guidelines shall document which
symbols have been selected.
(2) Element symbols 1 through 14, when combined with actuator symbols 1 through 16, represent
process control valves.
(3) Element symbol 2, when combined with actuator symbols 20 and 21, represent pressure safety
valves.
(4) Element symbols 15 through 19, when combined with actuator symbols 13, 14, and 15, represent
on-off solenoid valves.
(5) Element symbol 21, when combined with actuator symbols 1 through 16, represents a variable
speed control unit.
(6) Element symbol 21 represents a motor that manipulates or controls a process variable.
(7) Actuator symbols 1 through 16, when combined with element symbols 1 through 14, represent
process control valves and with element symbol 21 represents a variable speed control unit.
(8) Actuator symbols 17, 18, and 19, when combined with element symbols 15 through 19, represent
on-off solenoid valves.
(9) Actuator symbols 20 and 21, when combined with element symbol 2, represent pressure safety
valves.
(10) The symbols are applicable to all types of control valves and actuators.
5.3.5 Table 5.5 — Functional diagramming symbols:
(1) Signal flow is assumed to be from top-to-bottom or from left-to-right.
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(2) Symbols are shown in a vertical diagram format.
(3) Symbols shall be rotated 90 degrees counterclockwise in a horizontal diagram format.
(4) Insert signal processing symbol from Table 5.6 at (*).
5.3.6 Table 5.6 — Signal processing function block symbols:
(1) Symbols in small squares and rectangles are as used with symbol #1 from Table 5.1.2.
(2) Symbols in large rectangles are as used with symbol #5 from Table 5.5.
(3) Users engineering and design standards, practices and/or guidelines shall document which
symbol has been selected.
5.3.7 Table 5.7 — Binary logic symbols:
(1) True signals are equal to binary one, and false signals are equal to binary zero.
(2) Alternate symbols shall be used only for “AND’ and “OR” gates.
(3) Users engineering and design standards, practices and/or guidelines shall document which
symbol has been selected.
5.3.8 Table 5 8 — Electrical schematic symbols
(1) All devices are shown in the unactuated or de-energized condition.
(2) Switch contacts 2, 3, and 4 shall be actuated by:
(a) Hand.
(b) Actuator symbols 5 and 6.
(3) Actuator symbols 5 and 6 shall actuate switch symbols 2, 3, and 4.
(4) Switch symbols 7, 8, and 9.shall be actuated by:
(a) Hand.
(b) Actuator symbols 11 through 16.
(c) Bubble symbol for device or function assigned to actuate the switch symbol.
(5) Actuator symbols 11 through 16 shall actuate switch symbols 7, 8, and 9.
(6) Users engineering and design standards, practices and/or guidelines shall document which
symbol has been selected.
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Table 5.1.1 — Instrumentation device and function symbols
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.1. Shared display, Shared control (1) A B
C D
No. Primary Choice or Basic Process Control System (2) Alternate Choice or Safety Instrumented System (3) Computer Systems and Software (4) Discrete (5) Location & accessibility (6) 1 Located in field. Not panel, cabinet, or console mounted. Visible at field location. Normally operator accessible. 2 Located in or on front of central or main panel or console. Visible on front of panel or on video display. Normally operator accessible at panel front or console. 3 Located in rear of central or main panel. Located in cabinet behind panel. Not visible on front of panel or on video display. Not normally operator accessible at panel or console. 4 Located in or on front of secondary or local panel or console. Visible on front of panel or on video display. Normally operator accessible at panel front or console. 5 Located in rear of secondary or local panel. Located in field cabinet. Not visible on front of panel or on video display. Not normally operator accessible at panel or console. Copyright International Society of Automation Provided by IHS under license with ISA
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Table 5.1.2 — Instrumentation device or function symbols, miscellaneous
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.1. No Symbol Description 1 Signal processing function: Locate in upper right or left quadrant of symbols above. Attach to symbols above where affected signals are connected. Insert signal processing symbol from Table 5. Expand symbol by 50% increments for larger function symbols. 2 Panel-mounted patchboard plug-in point. Console matrix point. C-12 equals patchboard column and row respectively, as an example. 3 (7) (8) Generic interlock logic function. Undefined interlock logic function. 4 (7) (8) ‘AND’ interlock logic function. 5 (7) (8) ‘OR’ interlock logic function. 6 Instruments or functions sharing a common housing. It is not mandatory to show a common housing. Notes shall be used to identify instruments in common housings not using this symbol. 7 Pilot light. Circle shall be replaced with any symbol from column D in Table 5.1.1 if location and accessibility needs to be shown.
C
I
I
I
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Table 5.2.2 — Measurement symbols: measurement notations (4)
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3. Analysis AIR = Excess air H2O = Water O2 = Oxygen UV = Ultraviolet CO = Carbon monoxide H2S = Hydrogen sulfide OP = Opacity VIS = Visible light CO2 = Carbon dioxide HUM = Humidity ORP = Oxidation reduction VISC = Viscosity COL = Color IR = Infrared pH = Hydrogen ion = COMB = Combustibles LC = Liquid chromatograph REF = Refractometer = COND = Elec. conductivity MOIST = Moisture RI = Refractive index = DEN = Density MS = Mass spectrometer TC = Thermal conductivity = GC = Gas chromatograph NIR = Near infrared TDL = Tunable diode laser = Flow CFR = Constant flow regulator OP = Orifice plate PT = Pitot tube VENT = Venturi tube CONE = Cone OP-CT = Corner taps PV = Pitot venturi VOR = Vortex Shedding COR = Coriollis OP-CQ = Circle quadrant SNR = Sonar WDG = Wedge DOP = Doppler OP-E = Eccentric SON Sonic = DSON = Doppler sonic OP-FT = Flange taps TAR = Target FLN = Flow nozzle OP-MH = Multi-hole THER = Thermal = FLT = Flow tube OP-P = Pipe taps TTS = Transit time sonic = LAM = Laminar OP-VC = Vena contracta taps TUR = Turbine = MAG = Magnetic PD = Positive displacement US = Ultrasonic = Level CAP = Capacitance GWR = Guided wave radar NUC = Nuclear US = Ultrasonic d/p = Differential pressure LSR = Laser RAD = Radar = DI = Dielectric constant MAG = Magnetic RES = Resistance = DP = Differential pressure MS = Magnetostrictive SON = Sonic = Pressure ABS = Absolute MAN = Manometer VAC = Vacuum AVG = Average P-V = Pressure-vacuum = DRF = Draft SG = Strain gage = = Temperature BM = Bi-metallic RTD = Resistance temp detector TCK = Thermocouple type K TRAN = Transistor IR = Infrared TC = Thermocouple TCT = Thermocouple type T = RAD = Radiation TCE = Thermocouple type E THRM = Thermistor = RP = Radiation pyrometer TCJ = Thermocouple type J TMP = Thermopile = Miscellaneous Burner, Combustion Position Quantity Radiation FR = Flame rod CAP = Capacitance PE = Photoelectric = Alpha radiation IGN = Igniter EC = Eddy current TOG = Toggle = Beta radiation IR = Infrared IND = Inductive = = Gamma radiation TV = Television LAS = Laser = n = Neutron radiation UV = Ultraviolet MAG = Magnetic = = = MECH = Mechanical = = = OPT = Optical = = = RAD = Radar = = = = = = Speed Weight, Force ACC = Acceleration LC = Load cell = = EC = Eddy current SG = Strain gauge = = PROX = Proximity WS = Weigh scale = = VEL = Velocity = = = = = = = Copyright International Society of Automation Provided by IHS under license with ISA
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Table 5.2.3 — Measurement symbols: primary elements
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.2. No Symbol (4) Description Analysis
Conductivity, moisture, etc. Single element sensing probe. Analysis
pH, ORP, etc. Dual element sensing probe. Analysis
Fiberoptic sensing probe. Burner
Ultraviolet flame detector. Television flame monitor. Burner
Flame rod flame detector. Flow
Generic orifice plate. Restriction orifice. Flow
Orifice plate in quick-change fitting. Flow
Concentric circle orifice plate. Restriction orifice. Flow
Eccentric circle orifice plate. Flow
Circle quadrant orifice plate. Flow
Multi-hole orifice plate Flow
Generic venturi tube, flow nozzle, or flow tube. Notation from Table 5.2.2 required at (*) if used for more than one type. Flow
Venturi tube. Flow
Flow nozzle. Flow
Flow tube.
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Table 5.2.3 — Measurement symbols: primary elements
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.2. No Symbol (4) Description Flow
Open channel flume. Level
Displacer internally mounted in vessel. Level
Ball float internally mounted in vessel. May be installed through top of vessel. Level
Radiation, single point. Sonic. Level
Radiation, multi-point or continuous. Level
Dip tube or other primary element and stilling well. May be installed through side of vessel. May be installed without stilling well. Level
Float with guide wires. Location of readout should be noted, at grade, at top, or accessible from a ladder. Guide wires may be omitted. Level
Insert probe. May be through top of vessel. Level
Radar. Pressure
Strain gage or other electronic type sensor. Notation (*) from Table 5.2.2 should be used to identify type of element. Connection symbols 6, 7, 8, or 9 in Table 5.3.1 are used if connection type is to be shown. Bubble may be omitted if connected to another instrument.
PE
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Table 5.2.3 — Measurement symbols: primary elements
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.2. No Symbol (4) Description Temperature
Generic element without thermowell. Notation (*) should be used to identify type of element, see Table 5.2.2. Connection symbols 6, 7, 8, or 9 in Table 5.3.1 are used if connection type is to be shown. Bubble may be omitted if connected to another instrument.
Table 5.2.4 — Measurement symbols: secondary instruments
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.2. No Symbol (4) Description Flow
Sight glass. Level
Gage integrally mounted on vessel. Sight glass. Level
Gage glass externally mounted on vessel or standpipe. Multiple gages may be shown as one bubble or one bubble for each section. Use connection 6, 7, 8, or 9 in Table 5.3.1 if connection type is to be shown. Pressure
Pressure gage. Use connection 6, 7, 8, or 9 in Table 5.3.1 if connection type is to be shown. Temperature
Thermometer. Use connection 6, 7, 8, or 9 in Table 5.3.1 if connection type is to be shown.
FG
TE
LG
LG
PG
TG
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Table 5.3.1 — Line symbols: instrument to process and equipment connections
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.3. No Symbol Application 1 Instrument connections to process and equipment. Process impulse lines. Analyzer sample lines. 2 Heat [cool] traced impulse or sample line from process. Type of tracing indicated by: [ET] electrical, [ST] steam, [CW] chilled water, etc. 3 Generic instrument connection to process line. Generic instrument connection to equipment. 4 Heat [cool] traced generic instrument impulse line. Process line or equipment may or may not be traced. 5 Heat [cool] traced instrument. Instrument impulse line may or may not be traced. 6 Flanged instrument connection to process line. Flanged instrument connection to equipment. 7 Threaded instrument connection to process line. Threaded instrument connection to equipment. 8 Socket welded instrument connection to process line. Socket welded instrument connection to equipment. 9 Welded instrument connection to process line. Welded instrument connection to equipment.
(ST)
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Table 5.3.2 — Line symbols: instrument-to-instrument connections
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.3. No Symbol Application 1 (1) IA may be replaced by PA [plant air], NS [nitrogen}, or GS [any gas supply]. Indicate supply pressure as required, e.g., PA-70 kPa, NS-150 psig, etc. 2 (1) Instrument electric power supply. Indicate voltage and type as required, e.g. ES-220 Vac. ES may be replaced by 24 Vdc, 120 Vac, etc. 3 (1) Instrument hydraulic power supply. Indicate pressure as required, e.g., HS-70 psig. 4 (2) Undefined signal. Use for Process Flow Diagrams. Use for discussions or diagrams where type of signal is not of concern. 5 (2) Pneumatic signal, continuously variable or binary. 6 (2) (^) Electronic or electrical continuously variable or binary signal. Functional diagram binary signal. 7 (2) (^) Functional diagram continuously variable signal. Electrical schematic ladder diagram signal and power rails. 8 (2) (^) Hydraulic signal. 9 (2) (^) Filled thermal element capillary tube. Filled sensing line between pressure seal and instrument. 10 (2) Guided electromagnetic signal. Guided sonic signal. Fiber optic cable. 11 (3) Unguided electromagnetic signals, light, radiation, radio, sound, wireless, etc. Wireless instrumentation signal. Wireless communication link. 12 (4) Communication link and system bus, between devices and functions of a shared display, shared control system. DCS, PLC, or PC communication link and system bus. 13 (5) Communication link or bus connecting two or more independent microprocessor or computer- based systems. DCS-to-DCS, DCS-to-PLC, PLC-to-PC, DCS-to-Fieldbus, etc. connections. 14 (6) Communication link and system bus, between devices and functions of a fieldbus system. Link from and to “intelligent” devices. 15 (7) (^) Communication link between a device and a remote calibration adjustment device or system. Link from and to “smart” devices.
IA
ES
HS
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Table 5.4.1 — Final control element symbols
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.4. No Symbol Description 1 (1) (2) (^) Generic two-way valve. Straight globe valve. Gate valve. 2 (2) (3) Generic two-way angle valve. Angle globe valve. Safety angle valve. 3 (2) Generic three-way valve. Three-way globe valve. Arrow indicates failure or unactuated flow path. 4 (2) Generic four-way valve. Four-way four-ported plug or ball valve. Arrows indicates failure or unactuated flow paths. 5 (2) (^) Butterfly valve. 6 (2) (^) Ball valve. 7 (2) Plug valve 8 (2) Eccentric rotary disc valve. 9 (1) (2) (^) Diaphragm valve. 10 (2) (^) Pinch valve. 11 (2) (^) Bellows sealed valve. 12 (2) Generic damper. Generic louver. 13 (2) Parallel blade damper. Parallel blade louver. 14 (2) (^) Opposed blade damper. Opposed blade louver.
a)
b)
a)
b)
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Table 5.4.1 — Final control element symbols
Note: Numbers in parentheses refer to explanatory notes in Clause 5.3.4. No Symbol Description 15 (4) (^) Two-way on-off solenoid valve. 16 (4) (^) Angle on-off solenoid valve. 17 (4) Three-way on-off solenoid valve. Arrow indicates de-energized flow path. 18 (4) Four-way plug or ball on-off solenoid valve. Arrows indicates de-energized flow paths. 19 (4) (^) Four-way five-ported on-off solenoid valve. Arrows indicates de-energized flow paths. 20 (5) (^) Permanent magnet variable speed coupling. 21 (6) (^) Electric motor. Copyright International Society of Automation Provided by IHS under license with ISA
