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Thread: Limit water flow on Fire Hydrant Test

  1. #1

    Join Date
    Apr 2018

    Limit water flow on Fire Hydrant Test

    I have a static model, 2 Reservoirs as source points at 127' head (55 psi). Largest line size is 12". All junction node elevations set to 0. Billing data mapped to junction nodes as demands. No other control items. Fire Flow shows at some junctions up to 17,000 gpm available. Each source point has a 600 gpm pump, but when I put the pumps in,(600 gpm with 127' head single design point.), software cannot calculate fire flow solution. I get a 4002 error, disconnected junction added to selection set. but nothing shows. I just need a simple static fire flow output that reflects the capacity of the system, (ie. 2 600 gpm pumps at each source point.) Any thoughts?

  2. #2
    Forum Moderator

    Innovyze Employee

    Innovyze Employee

    Join Date
    May 2015

    It sounds like you have something that would cause an issue with even a standard run in your latest setup. If it cannot solve a standard run, then it would not be able to solve a fireflow run either.

    Take a look at where the disconnected junction is and if it has demand. If it has demand, the model cannot solve it it cannot satisfy the demands of that junction.

    Things I would check:

    1) What is happening with the disconnected node
    2) Do you have initial status settings keeping supply from reaching the demands? (i.e. are the pumps initially "closed" and with no controls cannot come on)
    3) Do the pumps run in a standard run without the fire ok? If not why? (pumps off, pumps at shutoff and can't flow?)
    4) It sounds like you may have added the pumps afterward, and supplied form Reservoirs initially. Reservoirs will allow an infinite supply, but with a design point pump curve the max flow from each pump would be at 2X the design Flow before the head gain would go negative. It is possible this pump definition and the limits of the pump curve are causing some issues. Try running a manual FF on a single jucntion and running a standard analysis and see if the model solves. I suspect FF demands above a certain value would cause the model to have difficulty in solving, but this can tell you for sure.
    5) Make sure to use a Full Status report with warning messages generated: This is the best for troubleshooting model issues. This will tell you the most information on what is occurring and where issues have occured. You change this on the Standard tab under Report Options
    (click if need larger image)
    troubleshoot image1.jpg

    You can also contact us at and we could investigate in more detail. We could either do a WebEx or have you send us your model. If you do, please refer to this thread in the email so we know it is related.

    Patrick Moore

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