Junction has demands and is disconnected from a reservoir or tank

Kim,

Where is pipe-104 in relation to the tank? Is the tank full or empty at the specific timesteps when the disconnection occurs? Is the network balanced? Is the FCV closed? (check the configuration, and consider if it should be something else, see this)

You can find further guidance in this article: System Disconnected or Junction Disconnected user notification messages

If this does not help, please provide a copy of the model and reply with steps to reproduce: Sharing Hydraulic Model Files on the OpenFlows Forum

What should I do to fix these disconnections? Thank you

Hi Kim,

I see you sent a copy of the model to me via private message. The reason why the system becomes disconnected at hour 7 is because that is the time when the tank (T-2) becomes empty. When this happens, WaterCAD/WaterGEMS assume a built-in altitude valve closes the downstream pipe, which then causes the system disconnection. This is one of the items mentioned in the article I linked to in my previous reply.

If you graph the inflow/outflow pipe flow and the tank Percent Full, you can see the downstream demands start to exceed the tank inflow FCV flow setting (since the demand pattern has an increasing multiplier at those times), causing the tank to drain rapidly. You can also observe this in the "Flow Supplied" and "Flow Demanded" columns in the Calculation Summary, where the flow supplied is a constant 146 m^3/day (due to the FCV setting at the only reservoir source) while the demand increased to over 800 m^3/day by hour 7.

You will need to check the demands/patterns to make sure they are correct and consider increasing the FCV setting, increase the tank storage capacity, or provide some other source to supply those demands.