User manual
Fault Action
10 There may be interference from static fields. Connect the pH
flow cell and the rear panel of the monitor using a standard
laboratory 4 mm “banana plug” cable.
11 Check that the pH electrode has been calibrated at the
correct temperature.
12 In organic solvents such as ethanol, methanol and
acetonitrile, stable pH measurements are not possible since
dehydration of the membrane will occur. We recommend
that the pH electrode is not used in applications using
organic solvents. Mount the dummy electrode instead.
13 Clogged liquid junction. Refer to section 4.8 Cleaning the
pH electrode.
pH values vary with varied 1 Replace the pH electrode.
back-pressure
Conductivity measurement
Incorrect or unstable reading 1 Check that the conductivity flow cell cable is connected
properly to the rear of the module.
2 Check that the pump operates correctly.
3 If temperature compensation is being used, check that the
temperature sensor is calibrated, and that the correct
temperature compensation factor is in use.
4 Check that the column is equilibrated. If necessary, clean
the column.
5 Check the operation of the mixer.
Baseline drift or noisy signal 1 There may be air in the flow cell. Use a flow restrictor after
the flow cell and check that the flow restrictor gives a back-
pressure of 0.2 MPa.
2 Check for leaking tubing connections.
3 Check that the column is equilibrated. If necessary, clean
the column.
4 Check the operation of the mixer and the pump.
5 Clean the flow cell according to the procedure in section
4.5 or 4.6.
Conductivity measurement
with the same buffer appears
to change over time 1 Clean the flow cell according to the procedure in section
4.5 or 4.6.
2 The ambient temperature may have changed.
Use a temperature compensation factor, see section B 2.4
Setting up conductivity temperature compensation, in
Reference information.
Absolute conductivity value
wrong 1 Turn the flow cell so the end with the screws is facing the pH
flow cell.
2 Recalibrate the conductivity cell.
3 Calibration solution, 1.00 M NaCl, not correctly prepared.
Prepare a new calibration solution and recalibrate the
conductivity cell.
Monitor UPC-900
User Manual 18-1125-55 Edition AE
29
Trouble-shooting 5