Tigerin
Unable to answer "What diameter is specified on the sign for this fire hydrant?" for https://osm.org/node/7820264668 via StreetComplete 37.1:

siehe Bilder

Attached photo(s):
https://westnordost.de/p/70190.jpg
https://westnordost.de/p/70191.jpg
https://westnordost.de/p/70192.jpg