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Default Design Constraints for Number of Barrels

What does the "Number of Barrels" in "Default Design Constraints" signifies?

What technical changes in the design one will observe while dealing with this particular constraint?

  • Hello Videet,

    My thoughts:

    Barrels are provided in Sewer Conduits when the Peak Flows at a certain time of days is exponentially more than the off Peak flows through the conduit; also when the duration of peak flow is very less as compared to the duration of off peak flows.

    During the Peak hours, the discharge through the conduits is high- resulting adequate self cleansing velocities through the conduits in order to avoid silting and sedimentation issues. However, during off peak hours, the discharge is very less and this results in sedimentation issues over the life of the network. It should be noted that the duration of peak flows is very less and hence adequate cleansing is practically impossible at times. Even slope can be a constraint.

    Provision of barrels within the pipes provides lesser wetted perimeter (or Area) during off peak hours resulting in adequate velocities to cleanse the pipe.

    Please refer to the following images for reference. Sewerage Network of GIFT City, Gujarat, India (our part of the world) is a case where Barrels were provided in a Sewer Conduits. However provision of Barrels is uncommon in South Asian countries in general owing to high capital investment involved in manufacturing of precast sewer conduits with barrels. Unfortunately, I lost the photo of the conduit I took when I was at GIFT City for consultation.

    I tried to share my 2 cents here, senior Bentley colleagues shall put in their inputs to this query soon.



    Answer Verified By: Videet Deshmukh 

  • Hello Videet,

    See the SewerCAD Help for a description:

    Allow Multiple Barrels?–When checked, allows the design algorithm to use more than one identical section in parallel, up to the specified Maximum Number of Barrels.

    "Barrels" refers to how many parallel pipes there are of the same shape and size of a particular conduit, represented by that conduit link element. One barrel means one pipe, two barrels means two pipes, for example. In most case when you specify a conduit element, it represents a single pipe. However there may be cases where you want the automated design tool to recommend two parallel pipes side by side as a design option, instead of one pipe of a larger diameter, for example.

    Local constraints can be set as well. For example you may have a run of several pipes where you want to look into the option of using two parallel pipes instead of one, in which case the local design constraint can be set for those specific conduits, with "allow multiple barrels?" checked and the max number of barrels constraint set to '2'.


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

    Answer Verified By: Videet Deshmukh