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Vladyman
March 12, 2017, 11:32 PM
I have a PRV set up to 45 psi.
When I run steady state simulation works fine

However, when I run in Extended Period Simulation (EPS) I get a problem, the downstream pressures are higher (image).
I tried both, the initial status button (the yellow pipe) and the Attribute -> valve ->setting

How do I set up a PRV valve for EPS?
385

Patrick Moore
March 13, 2017, 11:08 AM
Vladimir,

PRV's run the same in steady state or EPS except that rule based controls can

If the downstream pressure is higher than the setting and there is flow through the valve this is often an indication that either the initial status of the valve was set to "OPEN" or a simple or rule based control set the status to OPEN. When a valve has a status set to open it no longer acts like a control valve, but will be like an open pipe with headloss based on the ML coeff assigned.

If the downstream pressure is higher than the setting and the valve has no flow, the valve is closed because this is how PRV's work. They will automatically close if the downstream pressure is higher than the PRV setting and will only open and allow flow if the downstream pressure would fall below the setting in order to maintain the pressure setting indicated:

From the help file:
Pressure Reducing Valves (PRV) (javascript:TextPopup(this)) - A PRV limits the
pressure on the downstream end not to exceed a pre-set value when the upstream
pressure is above the setting. If the upstream pressure is below the setting,
then flow through the valve is unrestricted. Should the pressure on the
downstream end exceed the pressure on the upstream end, the valve closes to
prevent reverse flow.


I believe from your screen capture your issue is likely higher pressure but no flow in the valve. Your setting is 45 psi but the downstream pressure is 70-90 psi so it is automatically closed to prevent reverse flow through the valve.

Patrick



I have a PRV set up to 45 psi.
When I run steady state simulation works fine

However, when I run in Extended Period Simulation (EPS) I get a problem, the downstream pressures are higher (image).
I tried both, the initial status button (the yellow pipe) and the Attribute -> valve ->setting

How do I set up a PRV valve for EPS?
385

Patrick Moore
March 13, 2017, 11:12 AM
One last note: Check the things that are controlling the HGL downstream such as another valve possibly set to "OPEN" or something else unusually boosting the downstream HGL higher than it should be. Search for high headloss pipes as these are good indicators of accidental interties between pressure zones. If the pressures and flows were good in SS but not EPS, some setting was adjusted that would be causing the difference. This is often due an initial status or control for a pipe, valve or pump that creates a different operating condition that seen in the SS run.