Siemens RAPIDLAB 248, Operator'S Manual, Page: 59 / 135

Replacing the Reference Sensor Cassette
f. Carefully clean off any excess fill solution using clean, lint-free
tissue and deionized water. Push the clot removal line through
the vent hole to clear any fill solution crystals.
6. Check that ‘O’ rings are fitted to each side of the sensor and are in
good condition.
7. Refit the reference sensor top first, aligning the sensor contacts.
Press the bottom of the sensor into position. Make sure all the
sensors are seated correctly, then push the tensioner firmly home to
make a good seal. Lower the block cover, snapping it into place.
8. Lower the front cover and restart the 248 system. The 248
calibrates on return to the
Ready screen.
NOTE:
Following a change of reference sensor cassette it is normal for
the 248 to require a stabilization period of 30 minutes before optimum
performance is obtained. If an over or under range condition is present
on the pH channel there is probably an air bubble trapped in the
reference sensor. Remove the sensor and tap it until the air bubble has
been dislodged. Re–install the sensor.
Figure 3-24. Trapped Air Bubble in Reference Sensor
Replacing the Bottle Tubing
Equipment: Bottle tubing kit (Cat. 673250).
1. Drain the 248 and stop the system, Page 3-9.
2. Disconnect the three sets of bottle tubing from the manifold.
3. Install the new bottle tubing.
NOTE:
If you break or lose a bottle tubing connector there is a spare in
the Spares box.
4. Replace the Buffer Pack and Wash bottle:
a. Feed the bottle tubing into the neck of the bottles and into the solution.
b. Tilt the top of the bottle slightly away from you and slide into position.
c. Press the cap firmly onto the neck of the bottles.
5. Lower the front cover and press * to restart the 248.
6. Prime the 248, Page 3-9.
Maintaining the System Page 3-21
Trapped Air Bubble
Vent Hole