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Negative Pressures during EPS Analysis

I have an area of my model that has normal pressures when I run a Steady State analysis, and even at time step 0 in an EPS analysis. But starting at time step 0.75 hours and beyond in the EPS, the pressures in this area all become negative. I am not sure what is causing it. It could possibly have to do with the pump station and tank in the area (see Downing Ridge PS, Tunbridge PS, and Tunbridge Storage Tank), but I'm not sure. Could someone take a look at my model and help me out? It is uploaded onto the sharefile: DMWA System Model_updated. The problem area is highlighted in red in the screenshot below:

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  • Hello Dominick,

    In that case, what fills the tank in the actual system? Or if the demands are satisfied from another source besides the tank (or the hydropneumatic tank) is there some way to increase the head so the pressures are not so low?

    The tank is becoming empty to satisfy demands, but isn't able to be refilled. Once the tank is empty, the downstream demands need to be satisfied by sources further downstream, which is causing lower hydraulic grades due to headlosses. 

    Regards,

    Scott

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