Unable to answer "What diameter is specified on the sign for this fire hydrant?" – 195 (Pillar Fire Hydrant) – https://osm.org/node/12040458898 via StreetComplete 62.0:

Durchmesser muss hinzugefügt werden

Attached photo(s):
https://streetcomplete.app/p/318704.jpg
https://streetcomplete.app/p/318705.jpg
https://streetcomplete.app/p/318706.jpg
https://streetcomplete.app/p/318707.jpg
https://streetcomplete.app/p/318708.jpg