I think I found a mismatching definition of the key fire_hydrant:diameter.
According to the data objectfire_hydrant:diameter is “[t]he size of the connection fitting used to interface with the hydrant.” The German translation is matching this. These are the textes that are shown in the iD-Editor as a help.
According to the wikifire_hydrant:diameter is defined as “the nominal diameter of the underground pipe going along the street”. Here the German wiki page is also matching this.
I think the data object has a wrong description in it. It should be:
fire_hydrant:diameter: "This is the nominal diameter of the underground pipe going along the street that feeds (among other things) the hydrant. In some countries you can read it on the signboard near the hydrant: generally, it is the number on top of the sign. "
Am I right with my assumption? I do not want to change something without someone else having a look on it.
OT\ As a side bar, been moving fire hydrants and adding fire hoses on a large parking. All the fire hydrants have a couplings:type=UNI and are flagged by JOSM as an unknown value though it has over 8K times been used as a coupling value. Is that right or does this need a Github ticket? (There’s 22x ‘Uni’ too for inconsistency) /OT
The European and international designation equivalent to NPS is DN (diamètre nominal /nominal diameter/Nennweite), in which sizes are measured in millimetres, see ISO 6708.
Yes your write it without an unit -
no, DN sizes are not measured in millimeters, they are loosely related to millimeters and are without an unit, not only written without an unit
Be sure to document / correct the correct definition in the wiki though, unless you fancy having the same discussion some time later. (Or worse, years later, having to admit that the data has become implicitly ambiguous because it has never been correctly defined.)
Also, if you know and have photos how the fire hydrant (diameter) sign looks like in your country , adding a photo example or diagram to the wiki can only help mappers on-site to understand where to find the information. (If it isn’t yet, the StreetComplete quest that asks for a hydrant diameter could then be activated in that country.)
Thank you to everyone who helped varifiing the situation.
It seems that there is consensus that the changes according to my top post should be done. I startet editing it. Unfortunately I do not understand all the languages that were used. I do not want to add definitions in languages I don’t understand so I need your help.
If you are sure that the translations down below fit to couplings:diameter please add them. If you can think of a better translation feel free to rework them.
language | name | description
french | | La taille du connecteur du tuyau utilisé sur une bouche d'incendie.
portugese | hidrante:diâmetro | O tamanho do encaixe de conexão usado para fazer a interface com o hidrante.
ukrainian | Діаметр | Розмір з'єднувальної арматури, що використовується для під'єднання до гідранту
Of course you can also add any other language that you are familiar with. If you know languages beside German and English you can also add translations to fire_hydrant:diameter.
After do some quick research, most hydrant dimensions are not very meaningful. Color denotes pressure and or water source. The signed information is likely worthwhile to record. You can also count number and size of ports. Describe the overall shape of the hydrant itself. The only thong left is to measure the overall height. Anything else is an artifact of the design used. A handful of designs used a million times through out a region. It might be more useful to focus on cataloging these so they can be quickly identified.