A German standard of the German Institute for Standardization (
) for manhole tops with vents, class B125 (
From the standard overview:
This standard applies in conjunction with DIN EN 124 (
) and DIN 1229 for the summary of components for manhole tops of class B 125 with round or square frames for covering man entries and inspection chambers of drains and sewers.
Download document from Beuth Verlag (payment) https://www.beuth.de/en/standard/din-4271-1/154438248