Hello colleges,
I would like to share a model for pipe line i want to make protection from hammer using dipping tube and vacuum breaker to get the -ve pressure below -0.5 bars. Although I tried different volumes and position for the tank and the breaker, still the -ve pressure on the control valve remains out of range.
New folder (2).rarI would be happy for any suggestion/solution for this situation prefer using hydropneumatic dipping tube or/and vacuum breaker as protection devices
Hello Abdullah,
There are several issues with the model, incomplete data entry which you can complete to see the animated data in transient results viewer, time-history graphs.
To see the time-history graph, you need to define points in the calculation options to see time history graph so you can visualize what is happening at that particular elements, to see how the air volume is changing with time. . Also turn on the animation data so you can visualize the movement of pressure in Transients results viewer.
Using Transient Results Viewer animations for visualizing a transient simulation
Also in your current model hydropneumatic tank is inactive, after making it active, the vapor formation is mostly seen after the tank, at air valves, as the cavity at air valve closes and opens which effects pressures at air valves, please note that air valve give local protection.
Modeling Reference - Air Valves
In this case you are computing the model for a while and the volume keeps increasing, there is high volume of air, this can be an indication that the pressure at the air valve doesn't get above zero through the model run time. You typically want to see what happens when that air pocket collapses and the transient that results from these collapse occurs. This could mean you need to compute the model longer or introduce some way of adding head to the system so the hydraulic grade gets above the ground elevation. A surge tank is one option for the latter. See above air valve link to understand for how the air valve operates with the transient solver:
Regards,
Sushma Choure
Bentley Technical Suppport
Answer Verified By: Abdallah Magdy