The article discusses one of the ways to increase the effectiveness of fire-extinguishing foam at the automatic fireextinguishing system, in particular, the main focus is on the change of the hydrodynamic parameter equipment (sprinkler, nozzle). Today the workflow data sprinklers explicitly has not been examined and not regulated current technical regulations. In this connection it is interesting to conduct studies of the fluid mechanics in these sprinklers and suggest the ways to improve characteristics such as foam multiplicity and dispersion. As a result of work theoretical studies of the mechanics of fluid motion in the fire sprinkler with pre-aeration of extinguishing agent carried out. The equations of motion of the gas-liquid mixture in the injector for aeration extinguishing agent were solved.