TS EN 1861

TS EN 1861 defines the symbols and drawing rules used in system flow diagrams and piping and instrument diagrams for refrigerating systems and heat pumps. These technical drawings make the structure and functional flow of a plant readable at a glance, using a common visual language to show connections between components, control points, and flow directions.

Symbols and rules in technical documentation

The focus of this standard is to support consistent reading of diagrams used in refrigeration circuits and heat pump arrangements. System flow diagrams present the overall layout and functional relationships, while piping and instrument diagrams show the more detailed connections between equipment, pipework, measuring points, and control elements. That distinction matters in technical documentation because different project stages require different levels of detail, from design and installation through commissioning, operation, maintenance, and decommissioning.

Scope boundaries and where it is used

The standard applies to refrigerating systems and heat pumps, but it does not apply to systems where heat is extracted by an electrical circuit such as the Peltier effect. In general engineering practice, this kind of diagram standard helps designers, manufacturers, installers, and maintenance teams work from the same graphical conventions, reducing ambiguity in how equipment is connected, how symbols are interpreted, and how the system logic is documented over its service life.