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AR configuration

Dear ALL

I am evaluating the protection of an 8 klm pipeline. I performed the pump shutdown scenario. The results showed that the air pockets are formed in high position. So I added AR valve in the high positions and for that I used two configuration:

The first configuration is the following 

The length of the pipe that relates the junction and AR is 0.1 m

The second configuration is the following 

In terms of pressure envolope bioth configuration showed the same results. However in terms of AR pocekt, the first configuration eliminated air pockets formed along the pipeline. and for the second configuration  the results showed that the air pockets still excits in high position.

So which configuration reflects the reality. and why each configuration shows a different results in AIr pocekt profile.

Thank you

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  • Hello Abderahmen,

    In reality the Air Valve would be at a tee and sometimes the first configuration is adopted to replicate this. However, in this setup the air pocket will expand only on one side of the air valve as opposed to both sides when using the second configuration. Also, the extra small pipe connecting to the Air Valve may change the timing of transient wave interactions because it introduces a three-way junction and because it will typically be short and therefore susceptible to having its length or wave speed significantly adjusted during computation.

    For your first configuration check if you can see the air volume in the time histories. Since the Air Valve is located at a tee it wouldn't be part of the transient profile. Once you confirm, Tty both configurations and compare the differences in the transients for the event you are trying to simulate. If no notable difference is seen in the transient response, then use the approach that is easiest for you to manage in your model. For more details on this see the technote below for modeling Air Valves;

    Modeling Reference - Air Valves

    Hope this helps.


    Regards,

    Yashodhan Joshi

  • Technical material from the valve manufacturer will provide guidance on how to install the AR.

    I personally don't see any advantage from the second configuration.

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