Pipette controller with graduate reading plunger and lever assembly for gravity drainage

Claim 1

A pipette controller comprising: a cylinder; a piston disposed in said cylinder; a threaded rod operatively coupled to said piston; a spring arranged in said cylinder between the bottom thereof and said piston for biasing said piston to a predetermined position; a cylinder cap having a hole therein, said cap being coupled to said cylinder; a graduate reading plunger in thread engagement with said threaded rod and disposed through said hold in said cylinder cap; sealing means including a port for receiving the end of a pipette, the sealing means being disposed at the bottom of the cylinder for sealing the end of the pipette to the controller and placing the interior of the pipette in communication with a chamber defined by the piston and cylinder, said cylinder having a port for communicating with the atmosphere via a channel; an operable lever assembly adapted to selectively close the port of said channel, said operable lever assembly including a lever arm including a pair of lugs and a seal pad for selectively sealing said channel, a member having a pair of claws for engaging the lugs of said lever arm and projection means for providing a fulcrum for said lever arm, said controller providing natural drainage when the end of the lever arm remote from said pair of lugs is biased toward said cylinder.