modeling Dipping tube tank

Hello Bushra,

There are many factors that influence the performance of a hydropneumatic tank, including:

- initial pressure in the system
- initial gas volume
- tank inlet headloss
- ratio of losses (check valve bypass arrangement)

At first glance, I am not sure the variable elevation curve and other parameters are in alignment. Are you encountering any user notifications related to the tank configuration? You can read more details about how to set up the parameters of a dipping tube tank in this article: Modeling Reference - Hydropneumatic Tanks

Additionally, in some cases a single hydropneumatic tank alone may not be adequate to protect against transient pressures. It is possible that you may need a combination of equipment and transient control strategies. For a pump shutdown event, you may also need to assess the impact of turning the pumps back on and potentially expelling trapped air. Be sure to animate the profile path (regular path, not the pressure profile) to get a better understanding of how the system is responding to the transient event and the impact that the tank has. See: Using Transient Results Viewer animations for visualizing a transient simulation

Lastly, based on the initial pressure and network topography, it may not be possible to maintain the desired minimum pressure. I see that the problem areas appears to be on the right side of your profile. If the initial pressure is already very low, even a small transient downsurge wave can cause the minimum pressure constraint to be violated. You may need to double check that the constraint applies to the entire network, and make sure your initial conditions are reasonable. You may need to make a change to the initial conditions to keep the initial pressure higher. For example if you are pumping  up to boundary condition (tank or reservoir) at a high point where the pipe elevation is close to the tank/boundary elevation, you might need to consider a PSV (or top-fill tank via the Discharge to Atmosphere element, if ending at a tank), to increase the initial pressure. This may impact pump performance and you may also need to ensure that the initial pressure is not too high on the upstream side.

Hello Bushra,

There are many factors that influence the performance of a hydropneumatic tank, including:

- initial pressure in the system
- initial gas volume
- tank inlet headloss
- ratio of losses (check valve bypass arrangement)

At first glance, I am not sure the variable elevation curve and other parameters are in alignment. Are you encountering any user notifications related to the tank configuration? You can read more details about how to set up the parameters of a dipping tube tank in this article: Modeling Reference - Hydropneumatic Tanks

Additionally, in some cases a single hydropneumatic tank alone may not be adequate to protect against transient pressures. It is possible that you may need a combination of equipment and transient control strategies. For a pump shutdown event, you may also need to assess the impact of turning the pumps back on and potentially expelling trapped air. Be sure to animate the profile path (regular path, not the pressure profile) to get a better understanding of how the system is responding to the transient event and the impact that the tank has. See: Using Transient Results Viewer animations for visualizing a transient simulation

Lastly, based on the initial pressure and network topography, it may not be possible to maintain the desired minimum pressure. I see that the problem areas appears to be on the right side of your profile. If the initial pressure is already very low, even a small transient downsurge wave can cause the minimum pressure constraint to be violated. You may need to double check that the constraint applies to the entire network, and make sure your initial conditions are reasonable. You may need to make a change to the initial conditions to keep the initial pressure higher. For example if you are pumping  up to boundary condition (tank or reservoir) at a high point where the pipe elevation is close to the tank/boundary elevation, you might need to consider a PSV (or top-fill tank via the Discharge to Atmosphere element, if ending at a tank), to increase the initial pressure. This may impact pump performance and you may also need to ensure that the initial pressure is not too high on the upstream side.