# Pressure Drop

Written by Matt Milbury on . Posted in Pump

The difference in pressure between two points, usually caused by friction resistance in the pipe, but moisture can also affect it.

## Formula

A relationship for turbulent flow in commercial steel pipes is:

$$\Delta P = \frac{Q^{1.8} \mu^{0.2}}{C \cdot d^{4.8} \cdot \rho}$$

Where:

$$\Delta P$$ = pressure loss due to friction, psi per 100' of pipe

$$\mathrm{C}$$ = 20,000 for rough carbon steel pipe and 23,000 for smooth tubes.

$$Q$$ = flow rate, lb/hr

$$\mu$$ (Greek symbol mu) = Viscosity, cp

$$\rho$$ (Greek symbol rho) = density of the fluid, lb/ft3

$$d$$ = the internal pipe diameter, In