This German standard has been prepared by NA 012-00-04 GA "Gemeinschaftsarbeitsausschuss FNCA/NAL: Getränkeschankanlagen" ("Joint Working Committee FNCA/NAL Beverage dispensing systems"), which is formed by NA 012 of the DIN Standards Committee Chemical Apparatus Engineering (FNCA) and NA 057 of the DIN Standards Committee Food and Agricultural Products (NAL). In NA 057 DIN Standards Committee Food and Agricultural Products (NAL), the standardization work has been aligned within Working Committee NA 057-02-01 AA "Lebensmittelhygiene" ("Food hygiene"). The preparation of this standard took place with the cooperation of Working Group "Getränkeschankanlagen" ("Beverage dispensing systems") of BGN, Berufsgenossenschaft Nahrungsmittel und Gaststätten ("German Professional Association Foodstuffs and catering"). The standard applies to carbon dioxide warning systems; that is, electrical systems for warning of carbon dioxide (CO2) concentrations in ambient air that are hazardous to health. The power grid-operated systems discussed here are intended for use in beverage dispensing systems. These warning systems are used to prevent accidents when carbon dioxide is used as a dispensing gas. Leaking carbon dioxide represents a considerable hazard due to gas poisoning. Carbon dioxide, which occurs at low concentrations in the natural atmosphere, can quickly lead to unconsciousness when inhaled at higher concentrations and eventually to death. (CO2) is particularly dangerous because it is a colourless and odourless gas which, heavier than air, can accumulate in the lower part of rooms and does not easily disperse in the environment. The standard contains general requirements for carbon dioxide warning systems, such as function and alarm thresholds as well as indicating devices. In addition, the testing of carbon dioxide warning systems is a focal point of the standard. For this purpose, the standard conditions for testing with zero gas and standard test gas are specified. Furthermore, the test procedure is described in detail with aspects such as long-term stability, alarm triggering, insensitivity to fluctuations in temperature, air pressure and humidity as well as energy supply. Finally, requirements for the operating instructions to be supplied are standardized and numerous technical terms used are defined.