Calculated result
Engineering evaluation Calculation complete—verify project criteria Backflow-device loss margin (M_ΔP) 3 psi
Loss-budget utilization (U_ΔP) 80 % Engineering interpretation The entered device loss leaves 3 psi of the available loss budget.
Important limitations Screening calculation only. Adopted codes, project criteria, manufacturer data, measurement uncertainty, and professional engineering judgment remain controlling. Confirm the exact backflow assembly size, flow, manufacturer curve, test condition, strainer and valve losses, and code-required arrangement. Copy results Open printable PDF Download PDF
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Understand the calculation—not just the answer 2026-08-07 · Free Library Equations & method Engineering guide Reference data & sources
Governing relationships M_ΔP=ΔP_a−ΔP_d
U_ΔP=100ΔP_d/ΔP_a
Current substitution M_ΔP=15−12=3; U_ΔP=80%.
Calculation sequence
Step-by-step method Confirm the input boundary, formula symbols, and unit system. Apply the displayed equation to the user-entered values. Compare the screening result with project criteria, manufacturer data, and applicable standards. Equation legend
Inputs and calculated quantities
ΔP_a Available device-loss allowance — psi or kPa
ΔP_d Device pressure loss — psi or kPa
M_ΔP Backflow-device loss margin — psi
U_ΔP Loss-budget utilization — % Applications
How this calculation is used Building design Screen a documented plumbing-system relationship without embedding a protected code table.
Construction Check submitted or field values against the same transparent calculation basis.
Commissioning Reconcile measured and scheduled conditions before professional disposition.
Quality controls
Assumptions and limitations Assumptions User-entered values describe one documented system boundary and operating condition. All inputs use the displayed formula symbols and a consistent unit system. Limitations This transparent screen does not establish code compliance, equipment selection, or acceptance. Project criteria, manufacturer data, adopted codes, uncertainty, and professional judgment remain controlling. Field use
Verification procedure Confirm the system boundary and source of each input. Record representative values in the displayed units. Review the result against project criteria, manufacturer data, and applicable standards. Common engineering mistakes Mixing values from different pressure, temperature, flow, or time bases. Treating a screening result as a hidden design criterion or automatic pass/fail decision. Technical basis
References and source standards Need project-specific support?
Work with SVE Group Use this free tool for preliminary evaluation and field support. For project requirements, system analysis, commissioning, or engineering services, connect with SVE Group.
Visit SVE Group Contact the firm Engineering calculation disclaimer These engineering tools are provided for educational, preliminary evaluation, field verification, and commissioning support. Results depend on the accuracy of user-entered information and the assumptions stated for each calculation. Every colored status and comparison is a screening indicator only; project criteria, contract requirements, applicable codes, manufacturer instructions, measurement uncertainty, and authorized engineering judgment govern. The tools do not replace project-specific engineering analysis or the judgment of a licensed professional engineer.
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