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VERTICAL BEND IN WATERGEMS

Hi

I am new to WaterGems and have two questions.

first, when I want to model a water network do I need to assign appurtenances elevation or their top ground elevations?

I mean if I am modeling a valve I should indicate its elevation or ground elevation above the valve.

second, how can I model the vertical bend in watergems, and pipe slope is important in modeling or not?

please see the following capture.

 

  • Hamid,

    Yes, you should assign appurtenances elevations because the elevations you enter help to determine the correct pressure at that location once the model is computed. When you assign the elevation assign it the actual elevation of the valve, not the ground elevation above the valve. It might be useful to you to know that we define the elevation of junctions, valves, and pumps as the elevation at the centroid for these elements.

    Bends are modeled as minor losses in WaterGEMS. Adding an actual bend to a pipe doesn't do anything for the hydraulics of the model. The following wiki shows how you can add minor losses through the engineering library.

    communities.bentley.com/.../22947.will-the-minor-losses-associated-with-pipe-bends-be-automatically-accounted-for.
     
    Regards,
    Mark

    Mark

    Answer Verified By: Hamid.AKbari 

  • Thanks for your reply,
    But my question is: for example I have just a dtm file for the ground and a profile of the pipe network and appurtenances .
    how can I get the appurtenances elevation automatically?
    Also, for the vertical bend should I use the same minor loss which means the pipe slope is not important issue?

    Thanks

    Hamid
  • In WaterCAD/WaterGEMS, the elevation you use depends on where you want the pressure to be measured from. There is only a single elevation field (not an invert and ground) since that typically is not considered in a water system where the pipes are pressurized.

    If you have ground elevations from a DTM, it would make sense to use that for the elevation of *all* elements, to be consistent. So for a valve, you would then have the understanding that the reported pressure would be the pressure as measured from ground elevation.

    See more here:

    communities.bentley.com/.../9454.what-does-node-elevation-represent

    Of course, this means that a profile view of the elements would be showing the ground profile instead of the actual pipe profile, but you typically would not need to see this in a profile view for a water distribution system. If you have a need to see a profile view of the actual pipe elevations and slopes, then you would need to use the actual elevation of the pipes and nodes as the elevation (and then have the understanding that the calculated pressure is the pressure measured at the element location under the ground). If you need to do this, you could still use the DTM and perhaps globally edit the elevations and subtract an assumed buried depth.

    I'm not sure I understand your second question regarding minor loss at a bend - since the water is under pressure, it likely doesn't make a difference if the bend is in the horizontal or vertical direction.

    You may find more useful information on general model practice in our book Advanced Water Distribution Modeling and Management:

    pages.info.bentley.com/books


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Hamid.AKbari 

  • What kind of vertical bend are you talking about?

    If it say a 5 ft drop along a pipeline to go under a stream, then that extra length of the vertical drop doesn't make much difference.

    If you are talking about a vertical riser pipe in a 10 floor building plumbing system then the vertical distance is very important and the location of a valve in that vertical pipe is important.

    What do you mean by "appurtenances"?
  • Hi Tom
    Thanks a lot for your reply.
    Actually, I am talking about the urban watermain modelling not building.
    Also, for the appurtenances I mean the butterfly valve, air valve .

    Thanks

    Hamid