P&ID symbols.
Reference for the symbols Tagsight reads on P&IDs: field instruments, panel instruments, valves, actuators, control loops, off-page connectors, and equipment shapes. Each symbol page describes how it appears on the drawing and how the extractor handles it.
Instrument mounting symbols
Behind-panel mounted instrumentAn instrument symbol with a dashed horizontal line bisecting the circle, denoting an instrument mounted behind the panel. Inside the cabinet, not directly acces.Field-mounted instrumentA simple circle on a P&ID denoting a discrete instrument located in the field, accessible to the operator at the point of installation rather than mounted on a.Panel-mounted instrumentAn instrument symbol with a solid horizontal line bisecting the circle, denoting an instrument mounted in the primary control panel and directly accessible to t.Shared-display BPCS function blockA hexagon containing a tag denotes a function executing in the shared-display Basic Process Control System, BPCS, the DCS or PLC that runs the regulatory loops..SIS logic solver functionA rounded square with an inscribed diamond marks a Safety Instrumented System, SIS function, the protective layer that takes the process to a safe state when a.
primary-element
Coriolis flow meterA U-tube or curved bent pipe with the inlet and outlet returning to the same plane. Coriolis meters report mass flow directly, plus density and temperature as s.Level sight glassA vertical glass tube against a vessel wall, tagged LG. Mechanical-only level indication for the operator at the equipment. No wires, no PLC channel, never on t.Local pressure gaugePI in an instrument circle on a pipe tap marks a local mechanical pressure gauge. Mechanical-only like the level sight glass, intended for operator local indica.Magnetic flow meterA pipe section labeled MAG with a pair of inline electromagnetic coils. Magmeters work on conductive fluids and produce a clean linear signal without moving par.Orifice plate, flow elementA vertical line bisecting the pipe represents an orifice plate flow element. Pair it with a differential pressure transmitter, PDT or FT and you have one of the.RTD sensor, Pt100, Pt1000TE, RTD inside an instrument circle. Resistance temperature detectors are the dominant primary element below 600 °C because they drift less than thermocouples a.Thermocouple primary elementTE inside an instrument circle is the standard tag for a thermocouple primary element. Thermocouples cover the highest temperature range in process work, especi.ThermowellA protective sheath that the temperature element inserts into. Tagged TW separately from the TE that lives inside it. Same physical location, two distinct items.Venturi flow elementA pipe section with a tapered constriction in the middle. Venturi tubes recover pressure better than orifice plates, which matters on services where the permane.
valve-actuated
Control valve, pneumatic diaphragmA globe-valve body topped by a rectangular diaphragm bonnet. The most common control-valve symbology on a process P&ID. The air signal in the upper rectangle mo.Motor-operated valve, MOVA valve body topped by a small circle with the letter M denotes motor-operated actuation. MOVs handle large block valves, ESD service, and remote isolation wher.Pressure safety valve, reliefAn angle-pattern body with a coiled spring bonnet on top. The spring sets the cracking pressure. Once relieved, the disc reseats. PSVs are mechanical safety dev.Solenoid valveA globe-valve body with a small rectangle on top containing the letter S. Solenoid valves switch on a discrete signal. You'll find them on instrument-air supply.
valve-body
Ball valveA circle inscribed in a square represents the ball-valve body. Quarter-turn operation makes ball valves the dominant emergency-shutdown choice on modern P&IDs.Butterfly valveAn ellipse with a diagonal disc inside represents a butterfly valve. Compact, low-cost, suitable for large diameters where a globe or ball would be unwieldy.Check valveA triangle pointing in the direction of intended flow. Check valves prevent reverse flow and are mechanical-only. No PLC channel, no actuator.Gate valveA bowtie body with a vertical stem and handwheel marks a gate valve. Gate valves are isolation devices, fully open or fully closed, never modulated.Globe valveTwo triangles meeting apex-to-apex form the standard globe-valve body symbol. Globe valves throttle flow well and dominate control-valve service because of it.Knife gate valveA knife gate valve is drawn as a gate-valve bowtie body with a diagonal line marking the sharp gate blade. Like a gate valve it is an isolation device, fully op.
Symbol not listed.
If a symbol type you encounter on drawings is not covered here, send a note and we will document the extraction behavior.