Energy Equation - Pressure Loss vs. Head Loss

Calculate and visualize pressure loss and head loss in fluid flow systems using the Energy Equation. Includes major friction losses and minor dynamic losses for both laminar and turbulent flow regimes.

Calculator

Inputs

Flow Velocity (v) (m/s)

Fluid Density (ρ) (kg/m³)

Duct/Pipe Length (l) (m)

Hydraulic Diameter (dh) (m)

Friction Coefficient (λ) (-)

Minor Loss Coefficient (ξ) (-)

Acceleration of Gravity (g) (m/s²)

Absolute Roughness (k) (m)

Dynamic Viscosity (μ) (Ns/m²)

Results

Reynolds Number (Re)-- -

Relative Roughness (k/dh)-- -

Dynamic Pressure (ρv²/2)-- Pa

Major Pressure Loss (Δpmajor)-- Pa

Minor Pressure Loss (Δpminor)-- Pa

Total Pressure Loss (Δploss)-- Pa

Velocity Head (v²/2g)-- m

Major Head Loss (Δhmajor)-- m

Minor Head Loss (Δhminor)-- m

Total Head Loss (Δhloss)-- m

Flow Regime	Reynolds Number Range	Description
Laminar	Re < 2,300	Smooth, orderly flow. Friction coefficient λ = 64/Re. Roughness is negligible.
Transitional	2,300 ≤ Re ≤ 4,000	Flow varies between laminar and turbulent. Friction coefficient cannot be determined.
Turbulent	Re > 4,000	Chaotic, mixed flow. Friction coefficient depends on Reynolds number and relative roughness (k/dh). Use Colebrook Equation or Moody Diagram.

Material	Absolute Roughness k (10⁻³ m)	Absolute Roughness k (feet)
Copper, Lead, Brass, Aluminum (new)	0.001 - 0.002	3.3 - 6.7 × 10⁻⁶
PVC and Plastic Pipes	0.0015 - 0.007	0.5 - 2.33 × 10⁻⁵
Stainless steel, electropolished	0.0001 - 0.0008	0.000328 - 0.00262 × 10⁻³
Steel commercial pipe	0.045 - 0.09	1.5 - 3 × 10⁻⁴
Galvanized steel	0.15	5 × 10⁻⁴
New cast iron	0.25 - 0.8	8 - 27 × 10⁻⁴
Ordinary concrete	0.3 - 1	1 - 3.33 × 10⁻³
Coarse concrete	0.3 - 5	1 - 16.7 × 10⁻³