Astract: Vulcanian eruptions are frequent, small-scale, short-lived explosive volcanic eruptions, which are thought to be produced by impulsive sources. The experiments presented here, produced byinjectionsofmixturesofwater,alcoholorsaltandsolidparticlesintofreshwater,createdawide variety of turbulent flows from steady and impulsive sources. We focus on the experimental flows analogous to Vulcanian events ‐ unsteady, finite-volume releases of buoyancy (thermals) and momentum (puffs), and short releases driven by both momentum and buoyancy. Dimensional analysis, based on two controlling source parameters, total injected momentum (M) and total injected buoyancy (B), identified a universal scaling relationship for the propagation of the flows; the non-dimensional, time-varying velocity term (ut 1/2 /B 1/4 ), where u is flow front vertical velocityandtistimefromflowonset,varieswiththetime-varying,non-dimensionalratioofsource parameters (M/Bt), such that ut 1/2 /B 1/4 ¼ k(M/Bt) 1/2 . The quantitative relationship successfully describes experiments and several Vulcanian eruptions for a wide range of initial conditions. The utility of the relationship is demonstrated by estimating total mass erupted and vent mass flux as a function of time, two parameters important to hazards assessment, for the well-documented )