Upsurge is not getting control for network having flat terrain

Question

Hi Bentley, 
 I am doing surge analysis of a network having flat terrain. During power failure condition,there are both upsurge and downsurge available in the network. I used One-way surge tank, with this all the downsurge has been controlled while upsurge is still available. I animated profile for various path then i found that wave is reflecting from the tanks which generating upsurge. I did many iteration with all most all the protection device (as: check valve at the tanks and in between the junction, Hydro- Pneumatic tank etc.) to weaken the wave but not able to reduce the upsurge (particularly in the path 0Z-16B and 0Z-22). Please let me know why this upsurge is not reducing and which with device it will get reduce. 
 I uploaded hammer file( named: "PH-1") for your reference. 
 Regards, 
 Ankit Kumar

Jesse Dringoli · Answer

ANKIT KUMAR said: I used One-way surge tank, with this all the downsurge has been controlled while upsurge is still available. 
 Some amount of "upsurge" pressure is to be expected and may be within acceptable tolerance for your pipes. Using the latest version of HAMMER (10.03.05.05, I see you are still on 10.03.00.69), I examined both profiles and found that the maximum pressure is not very far above initial conditions pressure (0Z-22 has an increase of about 15 m above initial pressure and 0Z-16B about 25 m. The maximum pressures do not exceed 70 m. The downsurge low pressure waves drop the pressure much lower (though in most of the network it does not become negative). 
 What is the maximum pressure tolerance for your pipes (DI K7 seems to refer to pressure class C25-C40 here ). 
 For profile 0Z-16B, the transient pressure rises above initial pressure near the end of the network because of the wave reflection and interaction from the branch leading to reservoir 0Z-22. This can be seen by animating the profile path in the transient results viewer . Reducing the severity of the initial downsurge wave should help reduce the severity of the resulting upsurge wave after end boundary reflection. 
 As a quick example, if you increase the initial and maximum elevation of the surge tank by 5 m and increase the lateral pipe (P-1290) from 600 mm to 800 mm, the maximum pressure will drop by about 10 m.