Maintenance and Service 8-11
Correc t i n g Flooded O p t i cs
Due to the nature of the reservoir in the CPC, the inlet tube must not be
plugged for more than a couple seconds when the instrument is in
operation. In addition, the instrument should not be tilted more than 10º
when it is in operation. In these events the vacuum flow can draw fluid from
the reservoir through the entire flow path, including the optics.
Usually the first sign of flooding is the particle concentration decreases or
changes erratically. In addition, the vacuum may have trouble functioning,
you may see fluid in the vacuum lines, or you may hear a slurping sound
coming from the CPC.
If you suspect the CPC is flooded, shut off the vacuum pump or disconnect
the vacuum system. Follow these steps to dry out the instrument:
1. Drain the reservoir following the steps in the “Draining Butanol from the
Butanol Reservoir” section in this chapter.
2. Remove the cover from the CPC.
3. Inspect all tubing to make sure that no fluid is in the lines. If there is,
remove the tubing and blow out any fluid with clean, compressed air.
Tubing needs to be removed prior to cleaning to avoid other parts, e.g.,
pressure transducer, that could be damaged by compressed air.
4. With fill bottle disconnected, run the CPC for 48 hours with vacuum to
thoroughly dry out the optics.
5. Refill the CPC with clean working fluid.
6. While sampling room air, use an oscilloscope to check the pulse height
of the analog pulses from the CPC. See the “Viewing Analog Pulses”
procedure next in this chapter.
7. If the pulse height is not within a normal range, the CPC should be
returned to TSI to have the optics cleaned. Refer to “Returning the
CPC for Service” later in this chapter for directions on returning the
CPC to TSI.
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