Product(s):	HAMMER, WaterCAD, WaterGEMS
Version(s):	08.11.XX.XX and higher
Area:	Modeling

Problem

How can I model an RPZ device (reduced pressure principle backflow preventer)?

Solution - HAMMER (transient simulation)

Currently, HAMMER cannot directly model this device. One of two possible workarounds can be employed:

1) Place two check valve nodes and model a TCV valve between them that discharges to a reservoir or D2A. Develop a pattern of valve closure (for the TCV) based on when the reverse flow occurs.

2) Use a surge valve between the two check valve nodes, modeled as a SAV.

Solution - WaterCAD / WaterGEMS (EPS or steady state simulation)

In the context of a steady state or Extended Period Simulation in WaterCAD or WaterGEMS, most likely the relief valve component of the RPZ does not need to be modeled. So, you could consider modeling this with a GPV node element using data from the manufacturer for the flow vs. headloss curve, along with specifying that the adjacent pipe is a check valve (has check valve = true). See: How can I model a backflow preventer?

See Also

Article: How do I model devices, control structures, or other elements the software might not explicitly provide when modeling my system?

Forum: Distribution Sytem Wide Hammer and Transient Analysis of RPZ

Forum: RPBP Valve