A sprinkler is provided for a firefighting installation including a network of vacuum sprinklers. The sprinkler includes: a fixing connector, which allows the sprinkler to be connected to pipe work and has a nozzle; a fusible member; and a shutoff member for shutting off the nozzle, held in shutoff position by the fusible member. The fusible member is kept bearing against the shutoff member by a moveable bearing, capable of allowing the shutoff member to leave its shutting-off position when the pressure in the nozzle exceeds a predetermined pressure. An ejecting element for ejecting the shutoff member is mounted outside the nozzle and acts in a pulling sense on the shutoff member.