YSI 6 series User Manual page 122

Sondes
Membrane Installation Instructions
Use the schematic below as an aid in replacement of the YSI Optical DO membrane.
Sensing Membrane
Note: The following steps can be carried out with the probe either installed in the sonde or removed from it.
Avoid touching the sensing membrane (shown in the above drawing) during the procedure.
 Remove the wiper assembly from the 6150 Optical DO Sensor and set it aside for later use.
 Using the 1/16 inch hex driver supplied in the 6155 Kit, remove the three screws from the sensor
face as shown in the diagram above. Remove the old membrane assembly from the wiper shaft
and set the screws aside for later use.
 Remove the new sensor membrane assembly from its hydrated container and dry the backside (the
side with the cavity) completely. Be certain that there is no water remaining in the cavity which
holds the sensing membrane. Use lens cleaning tissue, a gentle stream of compressed air, or both
to assure that the membrane cavity is dry. Do not heat the membrane assembly.
 Make certain that there is an O-ring in place in the groove surrounding the sensor cavity.
 Place the sensor membrane assembly over the wiper shaft and align the holes in the membrane
holder with those on the probe face so that the sensor cavity is located over the optical fiber ends
on the probe face. Be absolutely certain that the sensor cavity lines up with the probe optics
before proceeding.
 Place one of the screws in a hole in the membrane assembly and rotate the assembly slightly as
needed to match the screw to the proper hole in the probe face. Partially tighten the screw using
the 1/16 inch hex driver.
 Insert screws in the other two holes of the membrane assembly, rotating slightly as needed to
match the screw to the hole in the probe face. Partially tighten the screws using the 1/16 inch hex
driver. Take care not to scratch the membrane surface.
 Tighten all three screws securely using the 1/16 inch hex driver. CAUTION: INSERT LONG
SHAFT OF THE HEX DRIVER INTO THE SCREW AND TURN WITH THE SHORT SHAFT
AS SHOWN IN THE DIAGRAM TO AVOID OVERTIGHTENING THE SCREWS.
 Replace the wiper on the probe shaft and tighten with the proper 0.05 inch hex driver.
YSI Incorporated Environmental Monitoring Systems Operations Manual
Section 2
Wiper Assembly
Membrane Assembly
2-116