Home Symbol library Diagram symbols P&ID & process diagrams P&ID & process diagrams
Line symbols for process diagrams: valves and actuators, pumps and equipment, piping and line types, instrument bubbles, signal lines, HVAC and annotations. Not certified against any standard.
Schematic symbols are drawn from scratch following the usual conventions of ISA-5.1, ISO 10628 and IEC 60617. They are not certified against those standards: check them against your company standard before using them in issued documentation. Each symbol’s note says what could not be verified.
All 444 Manual, check & relief valves 60 Control valves & actuators 58 Pumps, compressors & drives 15 Vessels, tanks & reactors 14 Heat exchangers & thermal equipment 12 Separation, mixing & solids processing 26 Conveyors & feeders 42 Pipe fittings & accessories 83 Lines, connectors & annotations 35 Instrument bubbles & tags 35 Primary elements, signals & functions 28 HVAC & ductwork 36
444 of 444 symbols
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Manual, check & relief valves 60
Angle valve Schematic Ball valve Schematic Butterfly valve Schematic Check valve Schematic Diaphragm valve Schematic Double block and bleed Schematic Four-way valve Schematic Gate valve Schematic Globe valve Schematic Knife gate valve Schematic Manual valve with handwheel Schematic Needle valve Schematic Plug valve Schematic Rupture disc (bursting disc) Schematic Pressure safety / relief valve (PSV/PRV) Schematic Three-way valve Schematic Pneumatic valve, fail closed (FC) Schematic Pneumatic valve, fail open (FO) Schematic 3-way ball valve, L-port Schematic 3-way ball valve, T-port Schematic Sanitary ball valve (tri-clamp) Schematic Bleed valve Schematic Float valve Schematic Isolation and bypass assembly (in-line item) Schematic Instrument needle valve Schematic Pinch valve Schematic 3-way plug valve Schematic In-line spring relief valve Schematic Slide gate (bulk solids) Schematic Car-sealed closed valve (CSC) Schematic Car-sealed open valve (CSO) Schematic Locked closed valve (LC) Schematic Locked open valve (LO) Schematic Normally closed valve (filled) Schematic Angle valve with handwheel (blowdown) Schematic Ball valve with lever handle Schematic Segmented V-ball control valve with positioner Schematic Butterfly valve with gearbox and handwheel Schematic Butterfly valve with lever Schematic Ball check valve Schematic Dual-plate (wafer) check valve Schematic Lift (piston) check valve Schematic Spring-loaded check valve Schematic Stop-check valve with handwheel Schematic Swing check valve Schematic Diaphragm valve with handwheel Schematic Gate valve with handwheel and gearbox Schematic Globe valve with diaphragm actuator and side handwheel Schematic Knife gate valve with handwheel Schematic 3-valve instrument manifold Schematic 5-valve instrument manifold Schematic Plug valve with lever Schematic Balanced-bellows safety valve Schematic Pilot-operated relief valve Schematic Safety valve with rupture disc on inlet Schematic Pressure/vacuum relief valve (PV vent) Schematic Closed valve (filled symbol) Schematic Vacuum relief valve (vacuum breaker) Schematic Control valves & actuators 58
Diaphragm actuator Schematic Electric motor actuator Schematic Piston / cylinder actuator Schematic Valve with electric motor actuator Schematic Control valve, pneumatic diaphragm actuator Schematic Pressure reducing valve Schematic Solenoid valve Schematic Double-acting piston actuator Schematic Hand lever actuator Schematic Manual actuator (handwheel) Schematic Diaphragm actuator with positioner Schematic Solenoid actuator Schematic Spring-return piston actuator Schematic Butterfly valve with rotary pneumatic actuator Schematic Control valve assembly with bypass Schematic Control valve with diaphragm actuator Schematic Control valve, fail closed (FC) Schematic Control valve, fail open (FO) Schematic Valve with manual handwheel actuator Schematic Control valve with motor actuator Schematic Control valve with positioner Schematic 3-way diverting valve with pneumatic actuator Schematic 3-way valve with solenoid Schematic 3-way mixing valve with electric actuator Schematic Angle valve with diaphragm actuator (fail closed) Schematic Angle valve with electric actuator Schematic Back-pressure regulator (self-acting, upstream sensing) Schematic Ball valve with electric rotary actuator Schematic Ball valve with pneumatic rotary actuator (double acting) Schematic Pneumatic ball valve with solenoid (on-off) Schematic Ball valve with spring-return pneumatic actuator (fail closed) Schematic Butterfly valve with electric actuator Schematic Butterfly valve with double-acting pneumatic actuator Schematic Butterfly valve with spring-return pneumatic actuator (fail closed) Schematic Butterfly control valve with positioner Schematic Pneumatic diaphragm valve (fail closed) Schematic Gate valve with electric actuator Schematic Gate valve with hydraulic actuator Schematic Gate valve with pneumatic cylinder (double acting) Schematic Globe valve with spring-diaphragm actuator (fail closed) Schematic Globe valve with spring-diaphragm actuator (fail open) Schematic Globe control valve with I/P converter Schematic Globe control valve with positioner Schematic Globe valve with modulating electric actuator and positioner Schematic Globe valve with hydraulic actuator Schematic Globe valve with double-acting cylinder (fail last position) Schematic Globe valve with spring-return cylinder (fail closed) Schematic Pneumatic globe valve with solenoid pilot Schematic Knife gate valve with electric actuator Schematic Knife gate valve with pneumatic cylinder Schematic Plug valve with electric actuator Schematic Direct-acting solenoid valve, spring return (NC) Schematic Latching (bistable) solenoid valve Schematic Solenoid valve with manual override Schematic Pilot-operated (servo) solenoid valve Schematic Self-acting thermostatic valve with bulb and capillary Schematic Pneumatic ball valve with limit switches (ZSO/ZSC) Schematic Control valve with position transmitter (ZT) Schematic Pumps, compressors & drives 15
Compressor Schematic Fan Schematic Electric motor Schematic Centrifugal pump Schematic Diaphragm pump Schematic Gear pump Schematic Positive displacement pump Schematic Turbine Schematic Roots blower Schematic Ejector / eductor Schematic Peristaltic pump Schematic Progressive cavity pump Schematic Submersible pump Schematic Liquid-ring vacuum pump Schematic Venturi tube Schematic Vessels, tanks & reactors 14
Column / tower Schematic Agitated reactor / stirred tank Schematic Silo / hopper Schematic Floating roof tank Schematic Horizontal vessel / drum Schematic Spherical tank Schematic Vertical vessel / tank Schematic Open hopper Schematic IBC tote Schematic Fixed-bed reactor Schematic Tank with heating coil Schematic Open tank Schematic Pressure vessel with manway Schematic Water well Schematic Heat exchangers & thermal equipment 12
Air-cooled heat exchanger (fin-fan) Schematic Plate heat exchanger Schematic Shell and tube heat exchanger Schematic Fired heater / furnace Schematic Boiler (fire-tube) Schematic Condenser (shell and tube) Schematic Cooling tower Schematic Draft-tube crystallizer Schematic Rotary dryer Schematic Evaporator (calandria and separator) Schematic Spiral heat exchanger Schematic Kettle reboiler Schematic Separation, mixing & solids processing 26
Cyclone separator Schematic Filter Schematic Agitator (motor, shaft and propeller) Schematic Vertical baler Schematic Basket centrifuge Schematic Decanter centrifuge Schematic Chimney / stack Schematic Circular clarifier Schematic Ram compactor (horizontal press) Schematic Jaw crusher Schematic Bag filter (baghouse) Schematic Flare stack Schematic Ball mill Schematic Hammer mill Schematic Paddle mixer Schematic Multicyclone (cyclone battery) Schematic Platform scale Schematic Tank on load cells Schematic Vibrating screen Schematic Wet gas scrubber Schematic Lamella settler Schematic Twin-shaft shredder Schematic In-line static mixer Schematic Eddy current separator (non-ferrous) Schematic Magnetic drum separator Schematic Magnetic plate separator in chute Schematic Conveyors & feeders 42
Belt conveyor Schematic Rotary valve (airlock) Schematic Screw conveyor Schematic Bucket elevator Schematic Inclined cleated belt conveyor Schematic Drag chain conveyor Schematic Rotary airlock with drive Schematic Inclined screw conveyor Schematic Silo with screw feeder Schematic Vibrating feeder Schematic Covered belt conveyor Schematic Belt conveyor with overhead magnet Schematic Belt conveyor with magnetic head pulley Schematic Belt conveyor with metal detector Schematic Belt conveyor with drive and flow direction Schematic Reversible belt conveyor Schematic Telescopic belt conveyor Schematic Belt weigher (conveyor scale) Schematic Belt bucket elevator with drive Schematic Chain bucket elevator Schematic Chain conveyor Schematic Two-way diverter (flap gate) Schematic Overhead trolley conveyor Schematic Dense-phase pneumatic conveying (pressure vessel) Schematic Dilute-phase pneumatic conveying (pressure) Schematic Vacuum pneumatic conveying Schematic 90° roller curve (plan view) Schematic Gravity roller conveyor Schematic Powered roller conveyor Schematic Jacketed screw conveyor (heating/cooling) Schematic Screw conveyor with drive Schematic Shaftless screw conveyor Schematic Twin-screw conveyor Schematic Vertical screw conveyor Schematic Slat (apron) conveyor Schematic Belt transfer point (transfer chute) Schematic Vibrating conveyor trough Schematic Apron feeder Schematic Belt feeder under hopper Schematic Loss-in-weight gravimetric feeder Schematic Rotary table feeder Schematic Screw feeder under hopper Schematic Pipe fittings & accessories 83
Basket strainer Schematic Expansion joint (bellows) Schematic Flange (pair) Schematic Blind flange Schematic Flexible hose Schematic Concentric reducer Schematic Eccentric reducer Schematic Sight glass Schematic Spectacle blind (figure 8) Schematic Steam trap Schematic Tee junction (connected) Schematic Vent and drain Schematic Vent silencer Schematic Y-strainer Schematic Long-radius bend Schematic Sanitary clamp joint (tri-clamp) Schematic Coupling (sleeve) Schematic Pipe cross (4-way junction) Schematic Open drain (funnel to sump) Schematic 90° elbow Schematic Flange pair with gasket Schematic Flexible hose with end couplings Schematic Buried pipe Schematic Electrically traced pipe Schematic Insulated pipe Schematic Jacketed pipe Schematic Steam-traced pipe Schematic End cap (closed end) Schematic Threaded plug Schematic Sample point Schematic Hydraulic seal (U-trap) Schematic Steam trap station (drip leg and trap) Schematic Temporary start-up strainer (cone) Schematic Reducing tee Schematic Union (dismantling joint) Schematic Vent to atmosphere (gooseneck) Schematic Floor drain with grate Schematic Drain with valve and plug Schematic Ball (articulated) joint Schematic Rubber expansion / anti-vibration connector Schematic Slip (telescopic) expansion joint Schematic Expansion joint with tie rods Schematic Universal expansion joint (double bellows) Schematic Expansion loop Schematic Cartridge filter housing Schematic Self-cleaning filter (motor and flush) Schematic Orifice flange pair (with plate and taps) Schematic Bolted flange joint (flange pair with bolts) Schematic Articulated loading arm Schematic Quick coupling (camlock type) male-female Schematic Hose reel Schematic Utility station with hose (air/water) Schematic Acoustic insulation (A) Schematic Cold insulation (C) Schematic Heat conservation insulation (H) Schematic Personnel protection insulation (PP) Schematic Floor / slab penetration Schematic Roof penetration with flashing Schematic Tank bulkhead fitting Schematic Pipe wall penetration Schematic Fire-rated wall penetration (fire stop) Schematic Wall penetration with sleeve and seal Schematic Cased pipe at road crossing Schematic Double-containment pipe with leak detection Schematic Pipe in covered trench Schematic Drip sight glass (vertical line) Schematic Sight flow indicator with paddle Schematic Sight glass with illumination lamp Schematic Duplex strainer (twin changeover) Schematic Magnetic strainer Schematic T-type strainer Schematic Pipe anchor (fixed support) Schematic Pipe guide Schematic Spring hanger Schematic Hot-water tracing (tracer tube) Schematic Steam tracing with insulation Schematic Inverted bucket steam trap Schematic Float steam trap Schematic Thermodynamic steam trap Schematic Thermostatic steam trap Schematic Tank breather with desiccant Schematic Vent with flame arrestor Schematic Vent with valve and plug Schematic Lines, connectors & annotations 35
Flow direction arrow Schematic Capillary tubing Schematic Line crossing (no connection) Schematic Electric signal line Schematic Pneumatic signal line Schematic Process line Schematic Off-page connector Schematic Piping specification break Schematic Callout with leader line Schematic Sheet connector (circle with reference) Schematic Off-sheet connector (incoming) Schematic Off-sheet connector (outgoing) Schematic Earth / ground symbol Schematic Equipment earthing connection Schematic Reversible flow arrow Schematic Flow arrow (open head) Schematic Air line (sample with label) Schematic Condensate line (sample with label) Schematic Gas line (sample with label) Schematic Main process line Schematic Secondary line Schematic Sloped pipe Schematic Steam line (sample with label) Schematic Utility line Schematic Water line (sample with label) Schematic Numbered note flag (hexagon) Schematic Revision cloud Schematic Revision triangle Schematic Specification change flag Schematic Future connection (provision with cap) Schematic Tie-in point Schematic Battery limit Schematic Existing / new limit Schematic Package limit (skid / vendor package) Schematic Spec break at flange Schematic Instrument bubbles & tags 35
Analyzer transmitter AT-501 Schematic Auxiliary / shared location bubble (accessible) Schematic Auxiliary / shared location bubble (not accessible) Schematic Computer-function bubble Schematic Control-room / DCS bubble (accessible) Schematic Control-room / DCS bubble (not accessible) Schematic Field-mounted instrument bubble Schematic PLC / programmable logic bubble Schematic Flow indicating controller FIC-102 (control room) Schematic Flow totalizer FQ-106 (control room) Schematic Flow transmitter FT-101 Schematic Flow control valve FV-103 (field bubble) Schematic Flow computing/converting relay FY-105 (computer function) Schematic Hand switch HS-901 (operator accessible) Schematic Hand valve HV-903 Schematic Power transmitter JT-701 Schematic Level alarm high LAH-406 (control room) Schematic Level indicating controller LIC-402 (control room) Schematic Level switch high LSH-403 Schematic Level switch high-high LSHH-405 Schematic Level switch low LSL-404 Schematic Level transmitter LT-401 Schematic Differential pressure transmitter PDT-207 Schematic pH analyzer transmitter AT-502 Schematic Pressure indicating controller PIC-202 (control room) Schematic Pressure safety valve PSV-203 Schematic Pressure transmitter PT-201 Schematic Speed transmitter ST-601 Schematic Temperature indicating controller TIC-302 (control room) Schematic Temperature transmitter TT-301 Schematic Weight transmitter WT-801 Schematic Unclassified alarm XA-902 Schematic Relay / state converter YY-104 (in PLC) Schematic Position switch, closed ZSC-103 Schematic Position switch, open ZSO-103 Schematic Primary elements, signals & functions 28
High selector function Schematic I/P converter (current to pneumatic) Schematic Integrating function Schematic Low selector function Schematic Multiplying function Schematic P/I converter (pneumatic to current) Schematic Square-root function Schematic Summing function Schematic ISA-5.1 letter legend table (minimal) Schematic Logic AND (diamond) Schematic Logic OR (diamond) Schematic Diaphragm seal with capillary Schematic Level gauge glass Schematic Level probe Schematic In-line magnetic flowmeter Schematic Orifice plate Schematic Pitot tube Schematic Pressure tap with root valve Schematic Rotameter Schematic Thermowell with temperature sensor Schematic Venturi tube Schematic In-line vortex flowmeter Schematic Capillary tubing (filled system) Schematic Electric signal line Schematic Hydraulic signal line Schematic Pneumatic signal line Schematic Software / data link Schematic Undefined signal / process connection line Schematic HVAC & ductwork 36
Air handling unit (AHU) block diagram Schematic Automatic air vent Schematic Hot water boiler (heating) Schematic Water chiller (refrigerant circuit) Schematic Cooling coil Schematic Heating coil Schematic Flexible duct connection (vibration isolator) Schematic Backdraft damper Schematic Fire damper Schematic Manual balancing damper Schematic Motorized damper Schematic Square ceiling diffuser (plan view) Schematic Ceiling diffuser (section) Schematic Flexible duct Schematic Rectangular duct Schematic Round duct Schematic Duct transition (reducer) Schematic Diaphragm expansion vessel Schematic Fan coil unit Schematic Air filter Schematic Return air grille Schematic Heat pump (refrigerant circuit) Schematic Plate heat recovery unit (cross flow) Schematic Rotary heat recovery wheel Schematic Humidifier Schematic Axial fan in duct Schematic Centrifugal fan (HVAC) Schematic Radiator (panel) Schematic Duct CO₂ sensor Schematic Duct humidity sensor Schematic Duct differential pressure sensor Schematic Duct temperature sensor Schematic Duct silencer (attenuator) Schematic 2-way motorized zone valve Schematic 3-way motorized zone valve Schematic VAV box with reheat coil Schematic
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