AbstractThe vortex nozzle, employing the radial pressure differential across a vortex can be effective in limiting the discharge of fluid or slurries from pressurized systems without using small throttling orifices which could plug readily.This paper deals with an investigation of vortex discharge devices which use this principle: It features measurements of velocities using a photographic trace technique. The measured radial distribution of mean tangential velocity departed from a free vortex pattern due to friction losses at the walls of the equipment. Empirical equations were developed for the tangential velocity and the flow, the coefficients being related to parameters of the design.