This invention relates in general to valves and in particular to a new and useful check valve for infusion and transfusion apparatus.
In infusion and transfusion apparatus, it is known to insert check valves at various locations into the flexible line of the apparatus. The check valves are to prevent the fluid from returning into the flexible line in certain instances. It is known, for example, to insert check valves into the flexible lines which are connected to the run-off connection of drip chambers. It is further known to insert check valves into distribution pieces such as Y-pieces.
The prior art valves are designed as ball valves, disk valves, or as duck's bill valves. These valves are complicated and expensive to manufacture. They also have various drawbacks. For example, ball valves close tightly only in a conical seat. Then, however, there is a risk of the ball becoming stuck. Disk valves have the drawback of being very position dependent. Further, the valve disk may get stuck on the valve seat. The function of both these valves largely depends on the pressure or flow, i.e. they operate satisfactorily only at certain differential pressures or flow velocities. In duck's bill valves, the opening pressure is indefinite.