The invention relates to an application of mechanics to medicine. It deals with improvements in vacuum dosing devices used in surgical centers and other hospitalization areas including intensive care units of hospitals.
The invention introduces a series of improvements in the operation of the instrument described in U.S. Pat. No. 13,437 (Ser. No. 23,472). Although the instrument disclosed in the above mentioned Patent has a vacuum saving function, it shows some imperfections in its operation as noted below.
(a) The closure produced by flattening the rubber tube is not perfect. As it collapses, said tube leaves in both corners (FIG. 1xe2x80x941), a space along the tube, through which the vacuum unit continues drawing in ambient air during the stand-by state. Due to its flattened shape, the rubber tube frequently does not perfectly fit in the tube cylinder thus leaving a space (2) which continues with the space mentioned in (a), and through which air is permanently lost.
The hole (5) that communicates the ambient air with the inside of the case (3), through the hole (4) in the case, and the latter with the vacuum system, permits a vacuum loss which, though small, is permanent.
As the aspirated material passes in front of the hole (5), a certain amount of said material (6) enters the case (3) contaminating the finger that occludes its hole.
During the production process, both solid pieces need to be connected to a soft rubber tube, and subsequently the resulting set, which is also soft, must be inserted and fixed to the case holes; this assembly operation is therefore complicated and slow.