Hach QC8500 Series 2, User Manual

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77
Troubleshooting
4. Turn the pump on. Press
NORMAL RUN
. The display must show a speed of 35 in
order to continue this test. Refer to section 3.2 on page 16 if the display shows
anything else.
5. Using an accurate watch or chronometer, measure the time the pump takes to make
ten (10) revolutions. Make sure the time is 50 seconds ± 1 second.
6. If the recorded time is less than 49 seconds or more than 51 seconds, review the
instructions. Otherwise, contact Technical Support or a local sales representative
for assistance.
6.12 Dye test
The purpose of running a Dye Test is to help diagnose a problem with the reagent flow or
hardware setup. If nothing is found, the problem is most likely chemistry related. It is
recommended to use Universal dye (
section 6.12.1 ) and an interference filter of 500 nm
or greater wavelength.
There are two important dye tests that can be performed. The first test is used to find flow
problems. The second test can help find a valve problem or partial clogs that could not be
detected with the first test. The latter test can also be used to determine whether the
sample loop is being filled properly.
6.12.1 Make universal dye
To make a universal dye:
1. In a one liter container, pour 7.5 mL or 0.25 fl.oz of each green, yellow, red and blue
food dye.
2. Fill the container with deionized water and shake it several times.
Note: Universal Dye is available from the manufacturer (Catalog No. 50959).
6.12.2 Dye test for determine flow problems
This test will help find blockages in the reagent lines or air leaking into the manifold.
Place all reagent lines, including carrier and sample probe, in the Universal Dye. Observe
how the dye flows through the tubing. If a clog is present, follow the recommendations of
section 6.5.1 on page 74 .
• Are any transmission lines pulsating? This might be caused by a partial clog. Make
sure the waste line is dripping into the waste container and not immersed in the
waste solution.
Note: The term pulsating refers to the dye moving forward and backward constantly, but still
moving towards the manifold. The tubing itself may also pulse.
• Does the dye suddenly stop moving forward, then move backwards? If the dye is
flowing back to the container, most likely there is a clog somewhere in that reagent
stream. Check the path of the solution from the reagent container to the waste
container located after the flow cell.
• Are any air bubbles in the transmission lines or tubing on the manifold? If that is the
case, check the connections prior to the location where the bubbles are visible. Look
for crimped tubing where the connection is made. Make sure two O-rings are in place
at every tee or union connector.
This test can also reveal any incorrect connections on the manifold or at the valve. A
particular line can be immersed in Universal dye solution and the others in deionized
water. Follow the flow of the dye to verify the correct path of that particular reagent.