# Resistance Coefficient

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Resistance coefficient, abbreviated as K, a dimensionless number, is how much resistance to the flow an obstacle has.  This is the opposite of flow coefficient which is how much flow capacity an obstacle allows.

## Resistance Coefficient formula

$$\large{ K = f_d \; \frac {l} {d} }$$
Symbol English Metric
$$\large{ K }$$ = resistance coefficient $$\large{dimensionless}$$
$$\large{ f_d }$$ = Darcy friction factor $$\large{dimensionless}$$
$$\large{ d }$$ = inside diameter of pipe $$\large{in}$$ $$\large{mm}$$
$$\large{ l }$$ = lenght of pipe $$\large{ft}$$ $$\large{m}$$
$$\large{ i }$$ = $$\large{ \frac{l}{d} }$$ = equivalent length of the obstruction $$\large{dimensionless}$$