YSI 6 series User Manual page 121

Sondes Section 2
YSI recommends the optical DO membrane assembly be replaced once a year in order to assure the
maximum accuracy for the sensor and the 6155 kit allows the user to carry out this replacement without
returning the sensor to the factory. The following section provides detailed instructions for replacement of
the optical DO membrane assembly on the YSI Optical DO sensor.
NOTE CAREFULLY: The 6155 optical sensor membrane has been shipped in a humidified
atmosphere and the package SHOULD NOT BE OPENED until immediately before membrane
replacement. Once the sensor membrane has been installed on the 6150 DO sensor as described
below, it is important to keep the membrane in an environment which is characterized by 100%
humidity. Thus, after replacement of the membrane and installation of the sensor system in your
sonde, the DO probe with attached membrane should be stored either immersed in water or in a
sealed calibration cup which contains enough water so that the atmosphere is water-saturated. See
sensor maintenance instructions below if you inadvertently leave the sensor in ambient air for a
period of more than 2 hours.
YSI Incorporated Environmental Monitoring Systems Operations Manual 2-115