# How to analytically estimate the pressure loss through an liquid injector?

A simple orifice and a pipe have well-documented pressure loss calculation.

But when an injector has complicated flow patterns, is it possible to break it down into simpler sections by which the pressure loss can be calculated?

Or are there procedures to estimate the injector pressure loss?

Or is empirical the only way to measure the pressure loss?

$\dot w = C_d A \sqrt {2g \rho \Delta p}$
so, trivial to arrange for $\Delta p$....but you have to get $C_d$ somehow.