I am using a PRV to control the pressure downstream. My model has 2 reservoirs. The PRV is placed on the pipe which isolates the loop upstream of it. This gives me a looped network upstream of the PRV connected to a reservoir (R-1). I have another reservoir (R-2) which is downstream of the PRV and another looped network is supplying water on the downstream. I had to use the PRV as the elevation of R-2 is much lower than R-1 and is causing water to flow into R-2, making it act as a storage. Also due to lower elevations downstream there is pressure beyond the permissible limit at the junctions. Now when I used the PRV the pipe it is connected on is giving me a zero flow. Why is this happening? Now the downstream network is being supplied by R-2 and the upstream is supplied by R-1 and looks like they are functioning independently on these two reservoirs.
Is there a better solution to tackle this scenario? How can i tackle the increase pressures downstream.
What are the hydraulic grades in R-1 and R-2? The control setting of the PRV should be slightly higher than the level in R-2 or R-2 will not allow it to open.
Another possibility is that you have a pipe that bypasses the PRV and connects -1 and R-2. This would show up as hydraulic grade downstream of the PRV higher than the PRV setting.
Make sure the PRV is Active.
THe hydraulic grade at R-1 is 124.5m and R-2 is 95.3m. I have set the Pressure limit at PRV as 3.8 bar and yes the pressure downstream is still higher and is at 3.9 bar at the junction just downstream of the PRV. R-2 is at 3.5 bar and I also checked that the PRV is active.
I am attaching a screenshot of how the network looks to make the query clear.
Convert the 3.8 bar to HGL units and add it to the elevation of the PRV to see the setting.
So I changed the setting type of PRV to hydraulic grade and defined the hydraulic grade setting as 93.42m (converted 3.8 bar to HGL units +elevation). R2 is at a hydraulic grade of 95.3m. The HGL downstream of the PRV is 94.8m. Not sure what I am missing.
If the tank level is at a higher HGL than the PRV setting, the PRV has no reason to open. If you want to see flow, raise the PRV setting to above 95.3 m,.