Surge vessel is keep draining even after increasing & down surge is also not controlling at all, kindly check the attached model For_Surge_PS_Variation_UDC_10.8_TB _IRR_Primary_IFC_07_11_2022.zip
Nagesh,
Looking at your profile, this is a system where you are pumping over a high point with no downstream storage. Once the pumps shut down, there is nothing to prevent the hydropneumatic tank from continuing to drain, until the pumps turn back on.
This is a common situation which is documented in its own article here: Negative pressures occur during a transient simulation no matter what protection is used
You may need to consider how long the pumps will remain off, and model a pump stop + restart per this article: Modeling a pump startup and shutdown transient event in the same simulation
Some other comments/observations:
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Thank you so much Jesse for your detailed observations & suggestions, will check the model considering your observations & will update as per your suggestion