Ysi 556 MPS Bedienungsanleitung PDF herunterladen (Seite 96)

YSI Incorporated YSI 556 MPS

Page 90

11. Maintenance

11.1 Sensor Care and Maintenance

Once the sensors have been properly installed, remember that periodic

cleaning and DO membrane changes are required.

11.1.1 DO Sensor

For best results, we recommend that the KCl solution and the membrane cap

be changed at least once every 30 days.

1. It is important to recognize that oxygen dissolved in the

sample is consumed during sensor operation. It is therefore

essential that the sample be continuously stirred at the sensor

tip. If stagnation occurs, your readings will be artificially low.

Stirring may be accomplished by mechanically moving the

sample around the sensor tip, or by rapidly moving the sensor

through the sample. The rate of stirring should be at least 1

foot per second.

2. Membrane life depends on usage. Membranes will last a long

time if installed properly and treated with care. Erratic

readings are a result of loose, wrinkled, damaged, or fouled

membranes, or from large (more than 1/8" diameter) bubbles

in the electrolyte reservoir. If erratic readings or evidence of

membrane damage occurs, you should replace the membrane

and the electrolyte solution. The average replacement interval

is two to four weeks.

3. If the membrane is coated with oxygen consuming (e.g.

bacteria) or oxygen producing organisms (e.g. algae),

erroneous readings may occur.

4. Chlorine, sulfur dioxide, nitric oxide, and nitrous oxide can

affect readings by behaving like oxygen at the sensor. If you

suspect erroneous readings, it may be necessary to determine

if these gases are the cause.

5. Avoid any environment that contains substances that may

attack the probe module and sensor materials. Some of these

substances are concentrated acids, caustics, and strong

solvents. The sensor materials that come in contact

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Ysi 556 MPS Bedienungsanleitung Seite 96