Standard Test Method for Calibration of Pyrheliometers by Comparison to Reference Pyrheliometers Ingestion-build-201039 ISO 20569 also specifies requirements

ISO 20569 also specifies requirements for their marking and labeling

it helps in determining the degradation in the coating as exposed to real working conditions

and their acceptance criteria

level of development and whether or not they have an environmental management system in place

BS EN 3645-004 is an international standard that specifies the characteristics of square flange hermetic receptacles in the family of circular electrical connectors with triple start threaded coupling

Standard Test Method for Calibration of Pyrheliometers by Comparison to Reference Pyrheliometers Ingestion-build-201039 ISO 20569 also specifies requirements