Changing PRV or PSV diameter does not change results

  Product(s): Bentley WaterGEMS, WaterCAD
  Version(s): 08.XX.XX.XX
  Environment: N\A
  Area: Calculations
  Subarea: N\A

Problem

Why do the results stay the same when changing the "diameter" field of a PRV or PSV?

Problem ID#: 55924
 

Solution

This will happen if the PRV or PSV is set to closed or active.

The diameter field for a PRV (or PSV) is only used when the valve is set to "inactive" (fully open). When the valve is active (controlling), the diameter does not matter, because the program is only concerned with the head loss necessary to acheive the desired downstream pressure.

One test that should be done is to set the PRV to inactive and enter an appropriate minor loss coefficient and diameter. The resulting head loss for this fully open condition should be compared to the head loss when the valve is active (throttling). If the head loss when inactive is greater than the head loss when active, it means that the valve is too small in diameter.

See Also

How does the Pressure Reducing Valve (PRV) work?

Why do I see such a large headloss through my FCV, PSV or PRV?



Anonymous
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