US Patent 7837447 Diluter pump for chemistry analyzers

A chemistry analyzer precision pump is disclosed. In one general aspect, it has a pump block that defines a first pump chamber with a fluid port at a first end, an opening for a piston at a second end, and a seal mount located between the opening and the port. A second, smaller, pump chamber also has a fluid port at a first end, an opening for a piston at a second end, and a seal mount located between the opening and the port. A first seal is mounted at the first seal mount and a second seal is mounted at the second seal mount. A first piston is mounted to reciprocate in the first pump chamber, past the first seal, and a second, smaller piston is mounted to reciprocate in the second pump chamber, past the second seal. The first and second pistons and the first and second pump chambers can be conically shaped.