Constant flow valve for fire protection facilities

A constant flow valve for a fire protection installation controlling discharge of fluid stored under pressure in cylinders (4) said valve comprising a body (2) with a fluid inlet hole (3), configured for being coupled to a mouth of the cylinder (4) containing the pressurized fluid, a fluid outlet hole (5), configured for being coupled to piping of the installation, and a sealing shaft (6) that moves between an open position and a closed position to respectively allow and block the passage of fluid inside the body (2) from the inlet (3) to the outlet (5), wherein movement of the sealing shaft (6) is controlled by a pneumatic release means (7), the release means (7) comprising at least one pneumatic actuation hole (11) that is in fluid communication with a hermetic chamber (10) via a non-return valve (12), the hermetic chamber having a slidable piston (14) disposed therein that transmits motion to the sealing shaft (6) based on a driving pressure exerted in the hermetic chamber (10) by a pressure source (8) via the actuation hole (11) and the non-return valve (12), wherein the fluid pressure at the outlet (5) is regulated by the driving pressure, regardless of the fluid inlet pressure from the cylinder (4), and wherein a release pressure is stored in a hermetic chamber (10) and the release pressure is kept constant during the entire discharge regardless of an inlet pressure of the fluid from the cylinder (4).