| 摘要 |
A cylindrical extractor for blood, one end face of which has a connection for a cannula, has a transverse wall with a central bore, and a piston guided, airtight, in the cylinder. The central bore guides the piston rod, and the transverse wall forms a rigid stop for the piston. The piston rod is releasable from a boss behind the piston, which is received into a counter-bored spigot in the dividing wall. The space between the piston seal and the zone of contact of the piston boss with the counter board spigot, is vented of air when the piston is retracted. The nipple forming the connection fro the cannula, tapers down to a tip sealed by a thin film, and is accommodated in a taper socket of a closure cap. This has a corresp. socket on its outer face with a spike at its bottom which bursts the film when this socket is applied to the nipple. An alternative embodiment has the nipple sealed by a solid tip extending beyond a circular notch at which the tip can be broken off. The venting arrangement prevents the compression of air in the cavity behind the piston during centrifuging, with the risk that when centrifuging is stopped, the pressure of the air makes the blood sample unusable. |
