Waters Prep Series Installation And Maintenance Manual page 17

sample forced past the pump seal from the discharge side of the pump. Wash
solvent flows from a reservoir to the wash pump and then to a cavity behind
the main pump seal of one pump head. From there, it flows to the cavity
behind the second head's seal. It then returns to the reservoir or proceeds to
waste, depending on your choice.
The wash pump runs whenever the controller is on, circulating solvent by
pushing a small volume along the flow path, one pulse per minute.
PrepLC controller
The figure below shows the Waters PrepLC controller, which controls solvent
composition, flow rate, sparging, and external events, during a run.
PrepLC controller front panel
Liquid crystal
display
Screen keys (4)
Function
keys (4)
The controller's rear panel, shown below, provides connection terminals and
communication ports for operating with external devices.
HOME key Cursor movement keys
Number keys (11)
Contrast
keys (2)
ENTER key
CLEAR key
Waters Prep series
On/off
switch
1-7