[Tagging] Feature Proposal - RFC - Process tanks.

Bert -Araali- Van Opstal bert.araali.afritastic at gmail.com
Sat Apr 10 16:12:57 UTC 2021

On 28/03/2021 15:41, François Lacombe wrote:
> Hi Bert,
> I see major issues with this reasoning, I explain why below.
> Le sam. 27 mars 2021 à 17:16, Bert -Araali- Van Opstal 
> <bert.araali.afritastic at gmail.com 
> <mailto:bert.araali.afritastic at gmail.com>> a écrit :
>     I don't see any added value for OSM to make a new top-level value
>     for process tanks.
>     As an engineer, I can say that any process tank, depending on the
>     stage in the process, is a storage tank.  Even if you would take
>     into consideration, that due to what appliances it has or how it
>     is build, doesn't give you a clue of whether it is used as a
>     process tank or just a storage tank.
> The main difference between storage and process tanks is that you get 
> the same output than input in the first and not for the last.
> At least any change in the contained substance is not expected in 
> storage tanks despite it could happen in some circumstances which 
> often should be avoided.
I can't disagree more François. Many storage tanks need a "process" to 
keep it's contents "unchanged". Some examples:
A liquid with suspension of some solids needs to be stirred during 
storage to maintain the suspension. If not you get flocculation, 
clogging ,sedimentation.  Other fluids might need heating to maintain 
the stored substance in it's desired state, heating being a "process".
Fuel tanks might have nitrogen blanketing to prevent explosive 
evaporation damps or oxidisation by air. Still, they remain storage 
tanks but removing the "conservation processes"  will result of the 
input not being the same as the output (not in chemical and not in 
physical characteristics).
Pumped ground water with high iron content will oxidise when exposed to 
air, changing it's odour, causing discolouring and even flocculation. 
When it is "stored" without some kind of preservation or conservation 
measures in place, what went in will not be the same of what came out. 
Same with bacterial growth in water storage tanks.  All these 
preservation or conservation measures are processing which many time 
takes place in the storage tanks.  Hard to distinguish or classify them 
as "process" tanks.
>     Many get disused for, primarily processing, others don't. 
>     Especially in water sewage faculties it is often difficult, even
>     for me as an engineer, if it is still in use as a process tank,
>     intended to be a process tank (because some storage tanks we just
>     add f.i. an aerator and it becomes a process tank ?).  Now you
>     expect that this tag is going to solve this problem, an issue
>     where even experts disagree many times.
> Tags are used to state objective differences seen on ground. A new tag 
> will not introduce new differences on ground but bring ability to 
> mappers to describe precisely what they seen.
> Then the point is not to find this difference every time but to be 
> able to describe it even once in the world.
> If a property lacks of consensus, OSM community should make a decision 
> like "An aerator is a process tank".
> Secondly, sewage processing facilities are often public service, then 
> sometimes open to visit, often with public information available 
> nearby or online. Then be able to transpose such public knowledge on 
> OSM should be considered as a common practice whatever complexity is.
This I agree, yet adding a process=* tag to any man_made=storage_tank 
can facilitate this.  Without expecting a mapper to be a chemist or 
process engineer.
>     A tank is just a tank, add some attributes to it if you are sure
>     and have seen proven that it is used for more then just storage,
>     then add attributes to it like in a process=* tag.
> We certainly agree on this one.
> One problem: none of us was there when it came to define 
> man_made=storage_tank (I would certainly had chosen another one for 
> this) and now storage_tank is unlikely to be changed due to its usage.
> Right now one of the main priority is to be consistent with existing 
> features.
I am not saying we should change storage_tank.  The opposite, there is 
nothing wrong with using the storage_tank value as most, if not all, 
process tanks can be considered as storage tanks at some point in time.
>     Essentially nothing is wrong to keep it under other top level
>     tags, being it water=reservoir, basin or pond or
>     man_made=storage_tank.  They all can become a process tank
>     somewhere in the processing of the fluid, they all are just
>     storage tanks in some stage of the processing. Keep it simple.
> I don't understand what you mean.
> Will someday a drinking water covered storage tank be part of any 
> processing? I guess no.

What I explained above, as well as a storage_tanl can be used for 
processing at some point in time the same applies to reservoirs and 
basins. Adding an attribute key process=* could be used with all of them 
in a consistently.


Bert Araali.

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