## Conduit calculations (pressure losses, velocity)

These calculations can help you to estimate the pressure losses, and flow velocity in the conduit (hose, pipe or tube) and check/correct conduit ID.

Calculations Notes:

- The recommended flow velocity in conduits you can find at the article Recommended flow velocity.
- The assumption: pressure losses on elbows, fittings at calculated conduit is zero.
- Height difference between IN and OUT points needs to calculate hydrostatic pressure what will be added to pressure losses, if IN point is below OUT (use positive value), or subtracted from pressure losses, if IN point is upper than OUT (use negative value). Use value “0” if height difference can be neglected.
- To find Darcy friction factor there are different formulas used:
- Darcy equation – for laminar flow.
- Churchill’s all-regime (1977) – the best approximation what I found for critical and transient flow.
- Haaland’s approximation (1983) to the Colebrook–White relation – for turbulent flow.