A fire sprinkler is the part of a sprinkler fire system that discharges water when the effects of a fire have been detected, such as when a predetermined temperature has been reached. The paper contains theoretical aspects of modern fire security systems (sprinkler systems), aspects which can be used in order to improve sprinklers quality, reduce production costs and also, to explain the operation processes that are evolving from the moment that the temperature activates the sprinkler, in chronological order.