1. What is Water Pressure from Flow Rate Calculator?

Definition: This calculator estimates the pressure drop in a pipe system based on fluid flow characteristics using the Hagen-Poiseuille equation.

Purpose: It helps engineers and plumbers determine the pressure loss in laminar flow conditions through cylindrical pipes.

2. How Does the Calculator Work?

The calculator uses the Hagen-Poiseuille equation:

Where:

• \( \Delta P \) — Pressure drop (Pascals)
• \( \mu \) — Dynamic viscosity (Pa·s)
• \( L \) — Pipe length (meters)
• \( Q \) — Volumetric flow rate (m³/s)
• \( r \) — Pipe radius (meters)

Explanation: The equation relates pressure drop to flow rate for laminar, incompressible flow in a pipe of constant circular cross-section.

3. Importance of Pressure Drop Calculation

Details: Accurate pressure drop calculations are essential for proper pump sizing, system design, and ensuring adequate flow rates in piping systems.

4. Using the Calculator

Tips: Enter the fluid viscosity (default 0.001002 Pa·s for water at 20°C), pipe length, flow rate, and pipe radius. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the viscosity of water?
A: Water at 20°C has viscosity of ~0.001002 Pa·s. For other fluids or temperatures, consult viscosity tables.

Q2: Does this work for turbulent flow?
A: No, this equation is only valid for laminar flow (Re < 2100). Different equations are needed for turbulent flow.

Q3: How does pipe radius affect pressure?
A: Pressure drop is inversely proportional to r⁴, so small radius changes have large effects on pressure.

Q4: What units should I use?
A: Use consistent SI units: meters for length/radius, m³/s for flow, Pa·s for viscosity.

Q5: Can I use this for non-circular pipes?
A: No, this equation is specifically for circular cross-sections. Use hydraulic diameter for other shapes.