ICS-90 Ion Chromatography System
5-10 Doc. 031851-05 12/04
5.4 Isolating a Restriction in the Liquid Plumbing
A restriction in the liquid plumbing will cause excessive system backpressure.
1. Begin pumping eluent through the system (including the columns).
2. Follow the ICS-90 flow schematic (see Figure 2-7
) and work backward
through the system, beginning at the cell exit. One at a time, loosen each
fitting and observe the pressure. The connection at which the pressure drops
abnormally indicates the point of restriction.
If the restriction has caused such high pressure that the system cannot be
operated, you must work forward through the flow schematic, adding parts
one at a time until an abnormal pressure increase (and hence, the restriction) is
found.
3. If the restriction is in the tubing or fitting, remove the restriction by back
flushing or by replacing the tubing or fitting.
5.5 Cleaning and Replacing Pump Check Valves
A dirty check valve causes an erratic flow rate. It may also cause the pump to lose
prime and/or be difficult to reprime.
1. Prime the pump (see Section B.13
). If the pump does not stay primed, go to
the next step.
2. Turn off the power switch on the ICS-90 rear panel and disconnect the power
cord.
3. Open the front door of the ICS-90.
4. Disconnect the tube fittings from both the inlet and outlet pump check valve
housings (see Figure 5-4
).
5. Using a 1/2-in box wrench or an adjustable wrench, carefully remove both
check valve housings from the pump head.
6. Place the check valves in a beaker of methanol and sonicate or agitate for
several minutes.
7. Rinse each check valve thoroughly with filtered, deionized water.
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