YSI 5200 - Manual (Page 114)

YSI Incorporated 112 5200 Recirculating System Monitor
Figure 11-2 5561 Probe Module - DO Sensor Replacement
2. Insert the long end of the hex key wrench into the small hole in the side of the probe module
bulkhead. Turn the wrench counterclockwise and remove the screw. (You do not have to remove
the screw all the way to release the sensor.)
3. Pull the old DO sensor module straight out of the probe module body.
NOTE: The DO sensor is not threaded, it is keyed, so it cannot be removed by twisting.
4. Insert the new DO sensor module. Make sure that the inside of the probe module sensor port and
the o-ring on the sensor are clean, with no contaminants, such as grease, dirt, or hair. The DO
sensor is keyed, or has a flat side, so that it cannot be aligned improperly.
NOTE: Make sure the DO sensor bottoms out before the set screw is inserted.
5. Insert the set screw into the small hole in the side of the probe module bulkhead, and turn
clockwise to rethread.
CAUTION: Make sure that you do not cross-thread the set screw. Use the hex key wrench to
tighten the screw in properly, making sure that the screw does not stick out of the side of the
probe module bulkhead. The probe sensor guard will not thread on properly and damage may
result if the screw is allowed to stick out.
NOTE: The DO sensor is shipped dry. A shipping membrane was installed to protect the
electrode. A new membrane cap must be installed before the first use. Refer to Section 4.5.1
Sensor Installation.
11.4.3 YSI 5564 pH and 5565 Combination pH/ORP Sensor Cleaning
Cleaning is required whenever deposits or contaminants appear on the glass and/or platinum surfaces of
these sensors or when the response of the sensor becomes slow.
1. Remove the sensor from the probe module.
2. Initially, simply use clean water and a soft clean cloth, lens cleaning tissue, or cotton swab to
remove all foreign material from the glass bulb (YSI 5564 and YSI 5565) and platinum button
(YSI 5565). Then use a moistened cotton swab to carefully remove any material that may be
blocking the reference electrode junction of the sensor.
Probe Guard
DO Sensor
Cable End
Set Screw
Hex Key
Wrench