How are flow results reported for a pipe when using taps and laterals on a customer meter element?

Product(s): WaterGEMS, WaterCAD
Version(s): CONNECT Editioin
Area: Modeling

Problem

How is the flow in a pipe calculated when using taps and laterals with a customer meter element?

Solution

This will depend on the placement of the lateral and/or tap. If you have a customer meter connected to the junction at the end of the pipe by a lateral, the flow in the pipe will simply be the demanded flow at the node (as well as any other downstream flow). However, if there are taps along the length of the pipe, the flow reported in the pipe will be different. 

Consider a case like the screenshot below.

Here we have a pipe with one customer meter connected to it with a tap. The flow reported in the pipe (P-2) will be half of the total demand on the customer meter. This is because the "demand distribution" property of the customer meter will be set to 50% by default, which means 50% of the customer meter's demand will be applied to the start node of the associated pipe (J-2) and 50% will be applied to the stop node (J-3). So, since half of the flow leaves the network at J-2, only the remaining other half will pass down the pipe (P-2), hence that pipe will show have the flow of the customer meter demand.

Now consider the case below.

Here the flow in the pipe will be the sum of the total demand at the downstream-most customer meter plus half the flow for the customer meter with the tap on it. (again, using the default 50/50 distribution for the customer meter on the left associated with P-2)

In summary, the flow in the pipe will be reported as half of the sum of all demands connected with a tap, plus the total flow at the downstream end of the pipe. .

See Also

Using LoadBuilder to assign Customer Meters to the nearest pipe using taps and laterals

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