[Tagging] Fire hydrants vs suction_point

Viking viking81 at tin.it
Tue Sep 5 22:24:24 UTC 2017


Hi all.

@Marc

> and is this tag well used? I am not able to judge whether values are realistic

Well, as in every tag, there are wrong values. But now, with a more clear description on the wiki, there will be less errors and future corrections will be possible.
Anyway all values of fire_hydrant:diameter=# should go in the new tag diameter=#, or whatever else we choose.


> what do others think? if somebody find it is not appropriate, I think that it would be desirable to split out the "meaning change"
> to validate the rest of the proposal.

At this point, after the discussion of pros and cons, I think that the "meaning change" has no more sense.


@Francois:

fire_hydrant:count=#  -->  devices=#

+1 I'm against grouping more than one hydrant one a node, but if we want to keep this possibility, devices=# for me is better.


> A pressurized hydrant : emergency=fire_hydrant + optional water_source=network + even more optional pressure=*
> A pillar connected to a water tank where water can be pumped from :
> emergency=fire_hydrant + water_source=water_tank + pressure=0
> A pipe going permanently in a river or a pond where water can be pumped from :
> emergency=fire_hydrant + water_source=pond + pressure=0

+1


@Martin:

> unfortunately this is not yet defined unambiguously

In hydraulics in general, the diameter is the nominal one [0] that is related but not equal to the inner diameter. On hydrants in particular, the number that is die-casted on them, is the nominal diameter of the undergound junction towards the water network.
Also couplings diameters are always nominal diameters of the threads [1].
Maybe it is enough to document on the wiki that when diameter=* is used for hydrants, it is referred to nominal diameter?


> Not sure about pressure=0 though, shouldn't that be 1? The wiki mentions also "suction" for dry hydrants 

In hydraulics, pressure normally is measured relatively to atmospheric pressure. So 0 is correct. However, to avoid misunderstandings, we can keep pressure=suction for these cases.

Best regards,
Alberto

[0] https://en.wikipedia.org/wiki/Nominal_Pipe_Size
[1] https://en.wikipedia.org/wiki/ISO_metric_screw_thread





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