The execc pressure due to water hammer can be calculated by the Joukowsky equation:
dP = Zh × Q
Where:
- dP is overpressurization, Pa;
- Q is the volumetric flow, m3/s;
- Zh is the hydraulic impedance, expressed in kg/m4/s.
Hydraulic impedance Zh defined by:
Where:
- ρ the density of the liquid, kg/m3;
- A cross sectional area of the pipe, m2;
- Beff effective modulus of compressibility of the liquid in the pipe, expressed in Pa.