Vinegar Buffer
Check on vinegar itself. Sometimes an older bottle of vinegar just doesn’t have enough acidity to cut
the pH in the cell properly. The vinegar my also contain mother of vinegar, a slimy, sometimes wispy
appearing cellulose substance produced by Acetobacter, the bacteria used to make vinegar. The
substance can cause blockages and can also create a false chlorine demand in the measuring cell.
First try a fresh bottle of vinegar. Do not refill an existing bottle of vinegar from a new bottle. Use the
new bottle, and throw away the old one. If the old one is contaminated with mother of vinegar, it will
be transferred to the fresh vinegar. If you find mother of vinegar in a bottle of vinegar, make sure to
dismantle and clean-out the cell block and the peristaltic tubing, or it will be a chronic problem.
Total Chlorine Readings
For total chlorine readings, check that you added the correct amount of Potassium Iodide (KI) to the
vinegar for the range of the analyzer, and that it was freshly mixed. Do not mix the KI and vinegar
ahead of time, as it deteriorates quickly. If you are working in ranges of 20 ppm and above, where you
may need up to 200 grams of KI per gallon, you should be using the second peristaltic pump option.
This will allow you to mix the KI with distilled water, and pump it separately.
Sample Cell
Dismantle the cell as described on page 37, and clean the inside surface of the copper ring. This is
especially important on initial startup, as the copper is 99% pure, and it oxidizes quickly, even after
only a few days of shipment to the installation site. A Scotch-Brite pad works best or you can use a 100
grit emery cloth, or a steel wool pad. Do not use a Brillo or detergent pad. If the analyzer has been in
service for some time, and there is a calcium buildup on the copper ring (due to high calcium in the
sample water), it can be dissolved with muriatic acid, or simply scrubbed off with sandpaper. If the
sample water is oily or greasy, such as in poultry processing waters, you should pre-filter the sample.
The oil or grease film on the cell can be cleaned off with most caustic based cleaners. Do not use any
that contain chlorine.
Sample Cell Problems
While you have the sample cell dismantled, check all the parts including the positive electrode (refer to
the positive electrode section below). There should be 150 PVC balls. If you are short a few, it’s not a
problem, but if it’s more than a few, the cell may not stay clean. Check for damage to the PVC balls and
mixer. If the mixer has damage on the tips or if the balls are slipping under the mixer, this would indicate
that the mixer paddle is set too high on the motor shaft. To set the gap correctly, refer to page 41. Do not
forget to put the PVC balls back in the cell.
If the mixer has damage on the sides, the balls are slipping between the mixer paddle and the
copper ring. This would indicate that the copper ring has reached the end of its useful life, and needs
replacement. The copper ring will slowly erode over time (usually several years or more), making the
wall of the ring thinner or mottled. Some sample waters are more aggressive than others, and copper
ring life-span will vary by location or application. This problem will usually show up initially as the mixer
motor jamming, or reversing by itself. It should be attended to before it damages the motor. If the mixer
has any signs of damage or wear, it must be replaced.
Troubleshooting
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FX-1000p
