Needle assembly

A needle assembly for maintaining a substantially constant pressure within a sealed receptacle when aspirating a liquid out of or dispensing liquid into said sealed receptacle, the assembly comprising:

• a first body;
• at least one guide rod supported by the first body for sliding movement between an extended position and a retracted position;
• a second body attached to said at least one guide rod such that said second body moves in conjunction with said at least one guide rod, the second body being relatively farther from the first body when the guide rod is in the extended position and relatively closer to the first body when the guide rod is in the retracted position;
• a biasing member biasing the guide rod to the extended position;
• a venting needle supported by said second body, said venting needle extending a fixed distance beyond said second body in a direction generally opposite the first body;
• and
• a liquid handling needle coupled to said first body so sliding movement of the guide rod toward the retracted position retracts the second body and the venting needle relative to the liquid handling needle.