Multichannel air displacement pipettor

A pipetting system, comprising:

• a pipette head comprising a multichannel air displacement system configured to aspirate and dispense liquids, a seal compression plate comprising a proximal surface, a set of o-rings associated with the seal compression plate, and a cylinder block plate, wherein:
• the multichannel air displacement system comprises pistons in respective cylinders and a displacement motor configured to reciprocally move the pistons in the respective cylinders in response to displacement motor commands;
• and
• the seal compression plate comprises bores each associated with one of the o-rings, each configured to receive a corresponding sealing tube associated with a pipette tip adapter that can be engaged with the pipetting system, and each co-axially disposed with a corresponding piston and cylinder;
• each of the bores of the seal compression plate comprises a counter-bore in which one of the o-rings is disposed;
• the depth of each of the counter-bores is less than the thickness of each corresponding o-ring;
• each of the o-rings comprises a proximal surface and the proximal surface of each o-ring projects above the proximal surface of the seal compression plate;
• the cylinder block plate comprises a distal surface disposed above the proximal surface of the seal compression plate;
• there is a gap between the distal surface of the cylinder block plate and the proximal surface of the cylinder block plate;
• the set of o-rings is disposed below the distal surface of the cylinder block plate;
• and
• the gap is less than the thickness of each of the o-rings.