SD flowpath selectors select one of 4 to 16 dead-ended streams. This example illustrates a high pressure SD valve (or Cheminert Model C5) used for HPLC column selection. This technique allows multiple columns to be installed permanently in the system, eliminating instrument downtime and leakage potential resulting from having to change columns repeatedly.
The SD valve selects only column inlets — the column outlets are connected to the detector via a low-volume manifold.
In step 1, sample flows from the injector through the SD valve to the inlet of Column 1, and through the manifold to the detector. In step 2, the SD valve is advanced to select Column 2, and so on through Column 8.
Step 1
Column 1 selected
Step 2
Column 2 selected
