## Moody Charts

The Moody chart module calculates friction factors for pipe flow.

The friction factor is computed using three different methods:

- The Darcy-Weisbach equation
- Colebrook's (non-linear) equation
- Churchill's explicit formula

INSTEDÂ®/Database also suggests a value. For laminar flows, the Darcy-Weisbach equation usually gives the most accurate results. For turbulent flows, the Colebrook and Churchill equations are the most suitable. The Churchill formula often gives good results for moderate to high Reynolds number flows. For the Colebrook method, INSTED uses a Newton-Raphson linearization. With this approach, the results are probably not reliable if the number of iterations is low (less than two) or very high (over 100). Finally, the friction value should not exceed 0.1 for turbulent flows or go below 0.005 for both turbulent and laminar flows, except for smooth pipes, where the friction factor may be several orders of magnitude less than 1.0.