Tigerin
Unable to answer "What diameter is specified on the sign for this fire hydrant?" for https://osm.org/node/9047374911 via StreetComplete 37.0:

kein Schild, daher Fotos zur Prüfung

Attached photo(s):
https://westnordost.de/p/69266.jpg
https://westnordost.de/p/69267.jpg
https://westnordost.de/p/69268.jpg