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Flushing Analysis

Hello Bentley Community,

I am performing flushing analysis for our water model network with 1515 active hydrants. I have the following questions 

1. Is there a way to run the flushing analysis that would indicate the order or sequence of hydrants to be flushed?

2. I want to know the discharge at each hydrant and not specify "flowing demand". On what basis do I specify the "flowing emitter coefficient" value?

  • Hello Shyan,

    1. I believe that order for the sequence for the hydrants is the order listed in the flushing manager. The flushing calculation is more to identify the results from flowing the hydrants than the order it is done. You can change the order in the flushing manager. This link has more information on this.

    2. The emitter coefficient is likely a product of the hydrant you are using. Some information can be found here or in the Help documentation related to hydrants and emitter coefficients. The Advanced Water Distribution Modeling and Management book may also be useful.

    Regards,

    Scott

  • If there was some simple rule-of-thumb to tell you the sequence of flushes, we would certainly already have it in WaterGEMS. But there are usually many sequences that all produce about the same results.

    Plus there are multiple reasons you may want to flush and each would have a different goals. Are you flushing to move deposited solids or are you flushing to bring water with higher chlorine concentration into an area? Do you think you need unidirectional flushing? 

    In general, the software shows you the effects of different flushing plans but the best tool for deciding on a plan lies between you ears.

    The only guideline I can give yo is Gangemi's Law, which I named after a guy I worked with on flushing, "Always flush with clean with behind you."

    Best wishes,

  • The purpose of flushing is to get rid of deposits in the water distribution network. I would like to know if the results for hydrant flushing in the browser table are displayed based on a logical sequence or if it is in a random order? Attached are the images for reference (First 3 hydrants in results browser of 1515). Default sequence of hydrant flushing in GEMS. Thanks!

    1.   2.  3. 

  • Shyam,

    The order of the flushing events in the Flushing Results Browser is based on the order they appear in the flushing study. This is also the order that the calculations use. As Tom mentioned, it is up to you to decide on the order of flushing events and you can rearrange them in the flushing study by right-clicking on an event and choosing to "shift up" or "shift down". This is mentioned in the article that Scott shared.


    Regards,

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