GE Sievers 900 Series Operation And Maintenance Manual page 206

Figure 40: Preparing to Back Flush the Sample Side Fluidics
4. Water will be flowing through the two pieces of disconnected pump tubing. Compare the
rate at which water drops from each piece of tubing.
If the water drops at the same rate, there is no sample-side obstruction and you can
proceed to Step 11 after replacing the pump tubing on the Y-fitting.
If the water drops more slowly through one of the pieces of tubing than the other, proceed
to the next step.
GE Analytical Instruments ©2009 206 of 236 DLM 90488-01 Rev. A