Parallel Backflow Preventers for Domestic Water

[nuuvox000]

Hello, HVAC & Plumbing engineer here. Anyone know if it's worth doing two backflow preventers in parallel (RP type)? We always do the pressure reducing valves in parallel (one large, one small, typically) to avoid "chattering" of the valve at low flows. I've never seen someone design two backflow preventers but I'm wondering if that's useful for that type of valve as well. Thanks.

 

[mk3223]

IMO, the purpose of the back flow preventer (BFP) is different from the pressure reducing valve. The BFP is to be closed and discharged through the relief valve once the flow direction is to be reversed, but won't be affected won't be affected because of the flow rate change.