Dispensing device for underwater respiration apparatus having a plurality of floating valves operating according to an improved system with pivots free from mechanical connections, said device being constructed in a single piece and comprising a central three-way distributor leading the compressed air or gas towards the center of the undersurface of a diaphragm of the floating valve, said diaphragm being located in a chamber containing a spacer member and, above the center, in a suitable central seat and loaded by a very weak spring, a service small valve with upright stem having fixedly mounted thereon an arm that operates in an upper chamber and is directly acted upon by the main control diaphragm, wherein the latter chamber communicates, through a suitable passage, both with the inspiration opening and with the expiration opening the latter containing a non-return valve, and also with the space below the undersurface of the diaphragm of said floating valve.