This European Standard specifies the symbols and drawing rules for system flow diagrams and piping and instrument diagrams to be applied to refrigerating systems including heat pumps. These diagrams represent the configuration and function of refrigerating systems and form a part of the complete technical documentation nessessary for designing, construction, installation, commissioning, operation, maintenance and decommissioning of a refrigerating system. This standard does not apply to refrigerating systems, where the heat is extracted by an electrical circuit, e.g. Peltier-effect.