1. What is a Pressure Drop Calculator?

Definition: This calculator estimates the pressure loss in a pipe system using the Hagen-Poiseuille equation for laminar flow.

Purpose: It helps engineers and technicians determine the pressure difference needed to maintain a specific flow rate through a pipe.

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 shows that pressure drop is directly proportional to viscosity, pipe length, and flow rate, but inversely proportional to the fourth power of the pipe radius.

3. Importance of Pressure Drop Calculation

Details: Proper pressure drop estimation ensures adequate pump sizing, system efficiency, and proper fluid flow in piping systems.

4. Using the Calculator

Tips: Enter fluid viscosity (default 0.001 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 viscosity value should I use for water?
A: Water at 20°C has viscosity of about 0.001 Pa·s. For other fluids or temperatures, consult viscosity tables.

Q2: Does this work for turbulent flow?
A: No, this equation is for laminar flow only. For turbulent flow, use the Darcy-Weisbach equation.

Q3: How do I convert GPM to m³/s?
A: 1 GPM = 6.309 × 10⁻⁵ m³/s. Multiply GPM by this factor before entering.

Q4: How do I convert pipe diameter to radius?
A: Radius = Diameter / 2. Ensure consistent units (meters for this calculator).

Q5: Why is radius to the fourth power so important?
A: Small changes in pipe diameter have dramatic effects on pressure drop due to this relationship.