PRV in close network-Epanet

[Arilu92]

Hi guys! New here. I've been working with the modeling of a potable water network in which I need to put several PRV because the topography is very steep and the pressures are above what I require by norms in ym country. The problem I'm having is that most of those valves are closing when I run the model, so it leaves some pipes without flow. I've been moving the valves around to find a way to make them work together and stop them from closing but I can't seem to find a solution. I'll appreciate any input you can give me

 

[hydrae]

Arilu92

Flow is not the goal of a PRV, pressure is. If the down stream pressure is above the set point, flow will be zero. If you have multiple PRV's supplying a single zone and the pipes are large compared to the demand in the zone, only 1 PRV will supply the area. In the field, the adjustment of the set point to just barely open is how multiple PRV's can flow into a single zone, the same can be done in the model

Hydrae[tt][/tt]

 

[coloeng]

You also need to make sure that the upstream and downstream nodes are correct for the PRV. If the line is drawn reversed, the PRVs will close.

 

[Arilu92]

Yes, I understand this. But I can't seem to find the right place to put the PRVs. I need to keep all pressure in the network under certain value, but also all pipes have a demand I need to supply. Maybe my original question is wrong, I understand why the model is doing what it is doing, but no matter what I do, I still can't place the valves to get the results I need. What is the best way to select the placement of the valves, or even to set the model so that my valves stop closing the way they are doing it roght now?

 

[hydrae]

From a practical point of view
As the water flows down the hill, when the pressure reaches 100 psi, put in a PRV with a set point of 40 psi
This will have a few services that require a separate PRV for their service, and services will not have less than 40 psi. Legally in the USA you have a minimum of 20 psi, plumbing code does not want more than 80 psi, bumping both setting up by 20 psi allows some flexibility and reduces the number of PRV stations.

If you are in SI units
100 psi ~ 6.8 bar
40 psi ~ 2.7 bar

Hydrae