A connection device for connecting a secondary drilling fluids circuit to a drilling element includes a radial aperture. A central body has a first connection portion forming a sealed connection to the secondary circuit. A second connection portion forms a sealed connection to the radial aperture and an intake duct conducts drilling fluids. A clamping system connects the connection device to the drilling element. One opening device is adapted to selectively open and close the radial aperture by acting upon a valve assembly. One coupling device connects the opening device to the valve assembly. The opening device selectively opens and closes the radial aperture by acting upon an obstructor of the valve assembly through rotary movement. The coupling device couples to a clamping element in the obstructor to transfer the rotary movement of the opening device to the obstructor to selectively and securely open and close the radial aperture.
