manufacturer:       LKB

model:                   2212 Helirac

annotation:           Dokumente engl.

PHYSICAL DESCRIPTION

The major components of HeliRac are the instrument cover, the chassis with the electronics and the drop delivery arm.

The cover is molded as a single unit. It is made of ABS plastic and coated with polyurethane. This renders the cover highly resistant to most solvents. (A chemical resistance list is given in appendix 1). In the center of the cover is a drain channel.

Tube position is determined via a circular code disc mounted underneath the cover. It is coupled via the hub to the cassette and they are driven together by a DC-motor. Three groups of holes are drilled through the code disc, one group for each type of rack available. A single hole corresponds to each tube position for the rack.

A sensor arm moves along a spiral track an the disc. It is furnished with three optical sensors (reflecting type), one for each group of holes. “Start” and "End" constitute unambiguous codes where all three sensors function simultaneously. The sensor arm is attached to the same shaft as the drop delivery arm. The two arms thus always have the same location and move at the same speed. When a run is ended the drop arm moves to the central hub and the instrument stops.

HeliRac is controlled by a microprocessor. It can be programmed either directly from the keyboard or remotely via the 2225 Chromatography Control Interface.

Apart from the working mermory HeliRac has four storage registers for program storage.

In the event of power failure the stored parameters will be protected for at least 1 hour. When the power is restored HeliRac will continue the run ,where it left off.