Full definition
Transient pressure surge caused by sudden valve closure or abrupt flow stoppage in a hydraulic or process line. The pressure wave travels at the speed of sound in the fluid (~1000 m/s in oil). Can reach 2-4× working pressure. Damages valves, gauges, and fittings. Mitigation: accumulators (energy absorption), slow-close controllers (>0.5 s), surge-dampening valves. Joukowski analysis: ΔP = ρ·c·ΔV.