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Why does some of TCV's in my model do not work?

I have a TCV in my model which do not work, for example when i close it, there is still a pressure in the node. But for some TCV's in my model they are all working.

I tried to redraw all the pipes and junctions but still the same thing happened.

File was uploaded.

  • Hello,

    What was the name of the file uploaded? I will take a look.

    Also, to which TCV are you referring?

    Dan

  • Hi Dan,

    Filename is SJM, and its TCV-49.

    Thanks

  • Hey,

    The only reason that TCV-49 shows a Pressure is because upstream of it there is a calculated pressure of 40 PSI. This is reflected in the TCV valve. Can you describe what you are trying to do with these TCV valves?

    I noticed the User Notification, "One or more initial relative closure values for TCVs did not match the assigned pattern initial value; the initial pattern value was used. Run a full validation for a full list of TCVs to which this applies."

    Make sure the initial relative closure value matches the pattern that you are currently using.

    Dan

  • Taking a closer look at this. If you are talking about the Junction J-207, the reason you are still seeing pressure in that node is because when the TCV valve is closed the model does not have a boundary condition to accurately calculate the HGL and subsequently pressure. You will notice the User Notification, "System Disconnected because of TCV-49." This is showing that the system is disconnected and therefore the logic is not able to calculate an accurate representation of the Pressure at J-207.

    In some cases in a real system this node might still be pressurized after closing the TCV valve. If you actually have an outflow from this node then you can use the following:

    You can create a Pressure Dependent Demand or an Emitter Coefficient on J-207 and when you run the model you will notice the Pressure drop to zero. This is simulating an outflow.

    Here is a wiki on Pressure Dependent Demands in case you are interested:

    Let me know if you have any other questions.

    Answer Verified By: Scott Kampa