To take a glance at all pocketEngineer software and OS requirements, click Software List.

Analyse pipe networks with ease — whether you’ve got closed loops or simple branched systems, LoopQP delivers fast, accurate results. 

What Does It Do?

LoopQP helps you calculate flow rates, pressure losses, velocities, and more for networks with one supply source and multiple outlets. Works for both:

• Looped networks (ring-main, campus plumbing, hydrant systems)

• Series / tree networks (branched water supply, irrigation, risers)

Just enter lengths, diameters, and demands in the table. LoopQP does the rest — automatically applying loop correction, hydraulic equations, and error checks.

Key Benefits

• Designed for engineers, students, and hobby users

• No complex formulas needed — the solver handles the math for you

• Saves time compared to manual Hardy–Cross calculations

• Reliable and tested for both simple and complex networks

• Clean tabular results — easy to read, print to PDF

How It Works

LoopQP is built around proven hydraulic principles to ensure accurate and stable results for both looped and branched networks.

1. Hardy–Cross Iteration
The program applies the Hardy–Cross method to balance flow in closed loops.
It starts with an initial flow estimate, then repeatedly adjusts each loop until the head loss and flow continuity are satisfied.

2. Darcy–Weisbach Equation
Head loss is calculated for each pipe using the Darcy–Weisbach formula.
The friction factor is determined iteratively from the Reynolds number and relative roughness for better accuracy.

3. Node Continuity Check
LoopQP automatically checks every junction node for mass balance and corrects any imbalance until total inflow equals total outflow.

4. Flow and Head Results
Once converged, the program outputs: Flow rate, Head loss, Velocity, Reynolds number, Friction factor.

5. Error Detection and Diagnostics
If a network contains disconnected pipes, undefined nodes, LoopQP identifies and reports them clearly.

5. Built-in Pipe Line Diagram Generator
LoopQP is capable of producing pipe line network diagram with adjustable drawing size to suit viewing and printing.   

Test case / validation with 5 Loops example 

To verify accuracy, LoopQP was tested on a five-loop network benchmark.  This example is taken from "An efficient iterative method for looped pipe network hydraulics" by Dejan Brkic and Pavel Praks. 

It is noted that only flow results are presented in the paper. In the diagram below, nodes numbering (s, a to k) are added for modelling purposes in LoopQP program. It is to observe that pipe segment c-j (ie, Pipe 6 in LoopQP) is not joined to pipe segment f-g (ie, Pipe 15 in LoopQP).

The following results are obtained by LoopQP program. The flow results obtained matches the results presented in the Dejan's paper.

Final Thought: As an engineer working on complex water distribution systems, I often found manual loop analysis tedious and error-prone.

I developed LoopQP to make that process simpler, faster, and transparent.
The goal was to create a lightweight, accurate tool that helps others analyze networks without expensive software or hidden steps.

What started as a personal project has grown into a practical solver to make looped pipe network analysis more accessible to everyone. 

Application Example: Analysis of Wet Riser System With & Without Ring Pipe

This example (Loop, Tree, Series) demonstrates the pipe frictional loss calculations with LoopQP program. The worst case (hydraulically the most unfavorable situated) is when 2 landing valves at 2280 L/m each are both discharged through the rising stack at the left side. It is easy to simulate various scenarios with LoopQP.

For general purpose pressure drop calculations, see ePF Loop (Windows)

If you need helper to draw isometric diagram, see drawPipe (Windows)

For fire sprinkler hydraulics, see tFIRE (Windows)