Junction vs. Hydrant

  Product(s): WaterGEMS, WaterCAD
  Version(s): and later
  Environment: N\A
  Area: Modeling



What are the differences between the hydrant and junction elements?

What are the pros and cons of using a hydrant versus a junction in your model?


1) The hydrants visually appear as hydrants, instead of the circle seen with the junction element

2) They are organized separately from junctions, so you can easily see only hydrant information by opening the hydrant flextable for example. You can also quickly create a selection set of only hydrant just by going to Edit > Select by element > Hydrant, then right click > Create selection set. In some cases where you would normally pick a selection set, you can actually simply select the "all hydrants" query instead.

3) You can enter an appropriate emitter coefficient for all hydrants, then choose which hydrant(s) are opened or closed based on the "hydrant status" field. This way, you only need to set the coefficient once. With a junction, you would need to set up separate demand alternatives and add/remove emitter coefficients. Note that emitter coefficients are not used with automated fire flow analysis and should be removed if you are doing that type of analysis.

See: How to use the "Hydrant Status" property in WaterGEMS and WaterCAD

4) You can account for head losses through the hydrant lateral without having to model the lateral pipe. Simply select "true" for "include lateral losses?" and enter the diameter, length and minor loss coefficient of the lateral. With the junction element, you would need to explicitly draw the lateral pipe out to the junction if you wanted to account for such losses. This adds to model complexity and to your total pipe count. If you have a limited number of pipes with your WaterCAD licenses, the hydrant feature could be very useful.

See: Calculating headloss through a hydrant lateral

See Also

Product TechNotes and FAQs

SELECTsupport TechNotes And FAQs

WaterGEMS and WaterCAD TechNotes and FAQs

  Original Author: Jesse Dringoli