Churchill correlation (friction factor) 
Piping
Systems
Equivalent length key pipe
components
Singularity coefficient key
pipe components
Partially filled pipe
Sonic Velocity
Valves types
Valves Cv
Control valve sizing for
gases
Pressure safety valves
Colebrook correlation
Churchill correlation
Velocity in pipes
Flow regimes
Orifice calculations

1. IntroductionThe friction factor is used to calculate the pressure drop
due to the flow of a fluid in a pipe. It represents the
interaction in between the fluid and the pipe. There are
different ways to calculate it, one can be graphical,
using a Moody graph, but for automating calculation it is
not practical, thus correlations are required. The Colebrook
correlation is usually admitted as being accurate
enough for most industrial application but presents a
difficulty as it does not explicitly express the friction
factor, that is why it may be interesting to consider
Churchill equation that allows to directly calculate the
friction factor. Note that the friction factor used here is
Darcy (also called DarcyWesibach or Moody) friction
factor. 2. Churchill equationWith :f = Darcy friction factor D = Pipe diameter (m) Re = Reynolds number ε = pipe roughness (m)
