Head of a closed-circuit diving breathing apparatus (rebreather)

A head (2) of a closed-circuit diving breathing apparatus (rebreather) comprising a body (5), tightly seated through a flange (5a) by means of a retaining ring (3) in a canister of the absorbent bed (4) equipped with a filling port aperture (4e) plugged with a plug with a spring (4d), and an upper air channel (4b) and a lower air channel (4c), provided with at least one bayonet connector (6), at least one oxygen connector (7), at least one diluent gas connector (9) or at least one dive computer connector (10) and in the body (5) of the head (2) there is an opening connected to the inside of the body constituting the mounting seat (29) of the button (20) and an opening connected to the inside of the body constituting the chamber (13) of the over pressure relief valve (12), characterized in that that the one-way over pressure relief valve (12) contains, in sequence, a valve piston (14), a spring (15), a seat of the one-way valve (16) and a one-way valve (17), the spring (15) supported on the seat of the one-way valve (16) pushes the piston (14) to the body (5) of the head (2), the one-way valve (17) is attached in the seat of the one-way valve (16) and all components are attached to the body (5) of the head (2) by means of a plug with openings (18), the connection of which to the body (5) is sealed with an o-ring (19).