Backflow Preventer Pressure Loss Calculator

Calculate pressure loss through fire protection backflow preventers (DCDA, RPDA) using manufacturer curves and NFPA 13/24 methods

Input Parameters

Results

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Pressure Loss
psi
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Outlet Pressure
psi
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Equivalent Pipe Length
ft
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Assessment
Note: Backflow preventers are required by most jurisdictions on fire service connections. RPDA assemblies have higher pressure loss than DCDA. NFPA 13 Section 23.2.3 requires pressure loss to be included in hydraulic calculations. Always use actual manufacturer Cv or loss curves.

Reference

Backflow Preventer Pressure Loss: dP = (Q / Cv)^2 Cv = valve flow coefficient (from manufacturer) Typical Cv: DCDA 6" ≈ 800, RPDA 6" ≈ 640 RPDA has higher loss than DCDA (~20% more) NFPA 13 & 24 require actual manufacturer loss curves. Equivalent length method also acceptable per NFPA 13.