Thermo Scientific Dionex UltiMate 3000 Series Operating Instructions Manual page 178

UltiMate 3000 Series:
NCS-3500RS and NCP-3200RS
Problem
Loading pump:
Flow fluctuation
(Cont'd)
Injection volumes are too
small and or of poor
precision. Air bubbles are
visible in the syringe.
Poor degassing (loading
pump)
UV signal drift during the
gradient
After switching from the
loading pump flow to the
nano flow, there is a drop in
the UV signal, and the signal
does not return to the initial
level fast enough.
Degasser noise
The temperature in the
column chamber does not
change for some time
although the temperature set
point has not been reached.
Page 170
Probable Cause
The piston does not contact the
magnet holder.
The piston seals are leaking.
The connection between the
buffer loop and the syringe valve
is loose.
Non-degassed wash solution is
used.
The capillaries or solvent supply
lines are leaking.
The degasser is not working
properly.
The flow rate is too high.
In applications with TFA, the
TFA concentration is incorrect. If
the signal drifts upward, solvent
B contains too much TFA and
vice versa.
The trap column is defective.
There is excessive dead volume.
The vacuum pump of the
degasser is running at high speed.
The ambient temperature is too
high or the set point is lower than
the specified difference to the
ambient temperature.
The ventilation slots on the NCS
are obstructed.
The compartment door is not
completely closed.
Remedial Action
Check whether the piston is
installed correctly. Reinstall
the piston if needed
(→ page 197).
Replace the piston seals
(→ page 194).
Retighten the connection and
flush the syringe
(→ Autosampler manual).
Degas the wash solution
(→ Autosampler manual).
Inspect the capillary and
solvent supply line
connections for leakage;
tighten loose fitting
connections.
Inspect the degasser for
indications for leakage.
Check the degasser vacuum.
Reduce the flow rate.
Increase or reduce the TFA
concentration as needed.
Replace the trap column.
Eliminate any dead volume.
Fill and degas all channels
(even if they are not used for
the application).
Select a higher set point or
reduce the ambient
temperature (for example, by
ventilating the room).
Make sure that the ventilation
slots are not obstructed in any
way.
To close, push the door
upward forcefully if
necessary.
Operating Instructions