TIP PROTECTION DEVICE

A safety cover which securably and reliably locks the tip of a cannula in an interior chamber within the safety cover. The cover comprises an elongate body having the interior chamber and an axial through hole which extends along the entire length of the body, through the interior chamber and through which the cannula is slidably received. Displacing elements are positioned within the interior chamber, each of which includes a hole for receiving said cannula therethrough, and which displaces upon retraction of the tip of said cannula, thereby preventing subsequent advancement of said cannula tip. In a first embodiment the displacing elements are annular rings. In a second embodiment, the elements are rigid balls having through holes. In a third embodiment, the displacing elements are a pair of conical elements, one of which is spring biased, each of which includes an offset hole. In each embodiment, it is preferable that the cannula should include a thickened rib adjacent to said tip, and the safety cover should correspondingly include an annular section in the rear portion thereof. The through hole extending through the rear portion has a diameter which is smaller than said thickened rib of said cannula whereby the cannula tip may not be retracted from the safety cover.