Abstract: A filter particularly for infusion and transfusion apparatus, comprises a housing having an inlet passage and a discharge passage spaced from the inlet passage. The housing includes a surface with a spiral flow passage defined thereon which is centrally communicated to the discharge passage. A filtering material is placed over the spiral in the housing which is made up of two parts which are interconnectable at the location of the spiral and which also act to hold the filter material in position. In an alternate embodiment, the housing of the filter is formed as a portion of a cannula. The inlet and outlet flow passages of the housing may be arranged to align axially, for example, on one side of the housing, or they may be offset.

Abstract: A piercing cannula of infusion and transfusion instruments, includes a housing having a lower liquid chamber defined therein and having an upper closure with an air opening on one side. A liquid member communicating with the interior of the housing extends outwardly through the closure directly alongside an aeration channel which has a lower end communicating with the opening. The housing includes a tubular portion defining an air inlet passage from the opening to the lower end of the aeration channel and a valve member is disposed between the liquid chamber and the lower end of the open aeration channel. The valve member comprises an upper inwardly tapered portion which is resiliently biased against the end of the tubular part defining the air passage.