Optical Oxygen Sensor Maintenance

One of the major advantages of optical oxygen technology is the reduced need for ongoing sensor maintenance. The following guidelines apply to the VisiFerm® family, VisiWater, and VisiTrace® products.

When connected to ArcAir® software, all of Hamilton’s powered sensors indicate their health status with simple traffic-light color coding. Yellow or red coloring can be an indication of errors, warnings, or hardware failures.

Sensor Health Indicators

Optical oxygen sensor health depends in large part on the condition of the optical cap. Applications that expose the cap to elevated temperature, pressure, or harsh chemicals can accelerate cap aging and reduce sensor performance. As the optical cap ages, calibration and maintenance for oxygen sensors become increasingly important for maintaining reliable sensor performance.

ArcAir® software provides real-time measurement quality indication as a percentage of top expected performance. The quality indicator accounts for both sensor and cap quality.

ArcAir Sensor QuickView Screen

The software warns the user to replace the optical cap if the quality drops below 35%. After cap replacement, the new cap should boost the quality indicator to at least 60%. Cap replacement should be followed with a proper zero point calibration and air calibration.

Replacing the optical cap is a simple procedure:

1. Unscrew the ODO cap from the shaft.
2. Remove the O-ring and replace it with a new one.
3. Firmly screw the new ODO cap onto the sensor shaft again.
4. Perform sensor calibration.

Optical Cap Replacement

Optical dissolved oxygen sensors rely upon a removable cap as part of their measurement principle. Over time this cap will degrade with continued exposure to sterilization cycles, strong chemicals, abrasion, and other process related factors. Cap quality can be tracked with the quality indicator in ArcAir Software. When the quality indicator reaches 60% ArcAir will provide a warning message "DO Replace Sensor Cap". Eventually when the quality indicator reaches 35% then the sensor will cease to function. At this point an ODO cap replacement is necessary for on-going measurement. Regular monitoring of the cap quality and replacement when required helps maintain reliable measurement performance.