ERD Symbols and Meanings

The vector stencils library "Terminals and connectors" contains 43 element symbols of terminals, connectors, plugs, polarized connectors, jacks, coaxial cables, and conductors.
Use it for drawing the wiring diagrams, electrical layouts, electronic schematics, and circuit diagrams.
"An electrical connector is an electro-mechanical device for joining electrical circuits as an interface using a mechanical assembly. Connectors consist of plugs (male-ended) and jacks (female-ended). The connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires or devices. An adapter can be used to effectively bring together dissimilar connectors.
There are hundreds of types of electrical connectors. Connectors may join two lengths of flexible copper wire or cable, or connect a wire or cable or optical interface to an electrical terminal.
In computing, an electrical connector can also be known as a physical interface... Cable glands, known as cable connectors in the US, connect wires to devices mechanically rather than electrically and are distinct from quick-disconnects performing the latter." [Electrical connector. Wikipedia]
"A terminal is the point at which a conductor from an electrical component, device or network comes to an end and provides a point of connection to external circuits. A terminal may simply be the end of a wire or it may be fitted with a connector or fastener. In network analysis, terminal means a point at which connections can be made to a network in theory and does not necessarily refer to any real physical object. In this context, especially in older documents, it is sometimes called a "pole".
The connection may be temporary, as seen in portable equipment, may require a tool for assembly and removal, or may be a permanent electrical joint between two wires or devices.
All electric cell have two terminals. The first is the positive terminal and the second is the negative terminal. The positive terminal looks like a metal cap and the negative terminal looks like a metal disc. The current flows from the positive terminal, and out through the negative terminal, replicative of current flow (positive (+) to negative (-) flow)." [Terminal (electronics). Wikipedia]
The shapes example "Design elements - Terminals and connectors" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

"The symbols and conventions used in welding documentation are specified in national and international standards such as ISO 2553 Welded, brazed and soldered joints -- Symbolic representation on drawings and ISO 4063 Welding and allied processes -- Nomenclature of processes and reference numbers. The US standard symbols are outlined by the American National Standards Institute and the American Welding Society and are noted as "ANSI/ AWS".
In engineering drawings, each weld is conventionally identified by an arrow which points to the joint to be welded. The arrow is annotated with letters, numbers and symbols which indicate the exact specification of the weld. In complex applications, such as those involving alloys other than mild steel, more information may be called for than can comfortably be indicated using the symbols alone. Annotations are used in these cases." [Symbols and conventions used in welding documentation. Wikipedia]
The example chart "Elements of welding symbol" is redesigned using the ConceptDraw PRO diagramming and vector drawing software from the Wikipedia file: Elements of a welding symbol.PNG.
[en.wikipedia.org/ wiki/ File:Elements_ of_ a_ welding_ symbol.PNG]
The diagram example "Elements location of a welding symbol" is contained in the Mechanical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Valves" contains 91 symbols of piping and plumbing valves.
"A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically valves fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure.
The simplest, and very ancient, valve is simply a freely hinged flap which drops to obstruct fluid (gas or liquid) flow in one direction, but is pushed open by flow in the opposite direction. This is called a check valve, as it prevents or "checks" the flow in one direction.
People in developed nations use valves in their daily lives, including plumbing valves, such as taps for tap water, gas control valves on cookers, small valves fitted to washing machines and dishwashers, safety devices fitted to hot water systems..." [Valve. Wikipedia]
Use the design elements library "Valves" to draw building plans, schematic diagrams, blueprints, or technical drawings of industrial piping systems; process, vacuum, and fluids piping; hydraulics piping; air and gas piping; materials distribution; and liquid transfer systems using the ConceptDraw PRO diagramming and vector drawing software.
The shapes library "Valves" is included in the Plumbing and Piping Plans solution from the Building Plans area of ConceptDraw Solution Park.

The vector stencils library "Dimensioning and tolerancing" contains 45 symbols of geometric dimensions and mechanical tolerances, geometric symbols, callouts, and text boxes and inserts.
Use these geometric dimensioning and tolerancing (GD&T) shapes to create annotated mechanical drawings.
"Geometric dimensioning and tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describes nominal geometry and its allowable variation. It tells the manufacturing staff and machines what degree of accuracy and precision is needed on each controlled feature of the part. GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features." [Geometric dimensioning and tolerancing. Wikipedia]
The shapes example "Design elements - Dimensioning and tolerancing" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Mechanical Engineering solution from the ConceptDraw Solution Park.