A constant flow regulator device for maintaining a constant flow of fluid when a variable fluid pressure is applied, comprising an inlet duct (506) for incoming fluid, a housing (500), and a movable partition (502) facing the inlet duct and being subjected to an elastic force. A fluid passage (510) of variable cross section area is formed between the inlet duct and the movable partition. The housing and movable partition form an inner compartment (504) in fluid communication with the inlet duct for establishing a fluid pressure inside the inner compartment approximately equal to the fluid pressure in the inlet duct. The size of the movable partition is significantly greater than the size of the inlet duct such that, in use, the partition is moved towards the inlet duct against the elastic force when the fluid pressure in the inlet duct increases to reduce said fluid passage cross section area, and vice versa, thereby maintaining constant fluid flow.