Pump System Curves Guide

A pump system curve plots the total head required by the piping system against flow rate. It consists of static head (constant) plus friction head (varies with flow squared). The intersection of the system curve with a pump's performance curve is the operating point (duty point). Plumbing Booster generates preliminary system curves for all pump system types.

The system head curve is calculated as: H = H_static + H_friction(Q) Where: - H_static = Static head (elevation difference + residual pressure) - constant - H_friction = Friction losses through pipes, valves, and fittings - varies with Q^2 At each flow rate Q: 1. Calculate friction loss using Hazen-Williams: hf = 10.67 x L x Q^1.852 / (C^1.852 x d^4.87) 2. Add static head 3. Plot H vs Q For multi-pump arrangements: - **Parallel pumps**: Flow rates add at the same head - curve shifts right - **Series pumps**: Heads add at the same flow - curve shifts up - **Per-duty-pump curve**: System curve divided by number of operating pumps

The duty point is where the pump performance curve intersects the system curve. At this point: - The pump delivers flow Q at head H - The system requires exactly head H at flow Q - This is the actual operating condition Plumbing Booster calculates the duty point and shows it in the Summary page with flow/head verification tables.

The Pumps module generates system curves automatically after TDH calculation: - **Total-system curve**: System head vs total flow rate for the entire pump arrangement - **Per-duty-pump curve**: System head vs per-pump flow (total flow divided by number of operating pumps) - Operating point (duty point) intersection - Flow/head verification tables showing calculated vs required values - Engineering-first summary with head breakdown and advisories - Visual representation in the Summary page The summary presents an engineering-first view: static head, friction head, residual pressure, and safety margin are broken down separately so the engineer can verify each component.