Troubleshooting - Siemens Maxum II PD PA AP Service Manual

Groove for
Figure 4-7
4.2.3

Troubleshooting

Faults, Causes, Remedies
Fault
All peaks appear smaller
Peaks are becoming wide and shifted to longer
times. Baseline becomes negative before injec‐
tion of sample.
Baseline becomes positive before injection of
sample.
Interruption in chromatogram: sample is not get‐
ting injected.
Peaks too small and too wide, especially those
with higher boiling points.
Injection quantity slowly rises until a double peak
results (with calibration medium). Poor peak
form, platform following peak. Increase in base‐
line. Visible discharge of sample.
The section of the injection stem that is normally
in the sample flow stream (near the notch) is
rough. Material wear on this section of the stem
is visible using a magnifier. The effect is signifi‐
cantly less on the rest of the stem.
Thin scratches are visible (with a magnifying
glass) on the stem near the sample groove.
These scratches run along the stem for several
millimeters.
Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001
Groove for
sample-flow
unit
O-ring
Liquid Injection Valve Body
Causes
Sample flow unit (15) or injection
blocked. Buildup of material on in‐
jection stem.
Vaporizer (16) is contaminated.
Gasket (14) between sample flow
and vaporizer is leaking.
Leaky pneumatic actuator, grease
used up, O-rings (4) damaged, con‐
trol pressure too low.
Heating plate is faulty. Vaporization
temperature too low.
Worn gaskets (14) and/or stem (6).
Corrosive sample
Sample is contaminated by particles
(most frequent case). The particles
get lodged in the gasket and scratch
the stem during injection.
Label for
Dosing
Volume
Alignment Groove
for attaching to
Control Cylinder
using hex set
screws
Remedy
Clean injection hole, stem (6), va‐
porizer (16) and sample flow unit
(15).
Replace gaskets (14) if necessary.
Clean pneumatic actuator, replace
O-rings, and grease sliding surfa‐
ces and O-rings.
Replace heating plate. Set higher
equalization temperature.
Replace gaskets (14) or stem (6).
Possibly replace injection stem (6)
by version made of another material
more compatible with the sample
chemical, such as Hastelloy.
Check filter from sample system
and replace if necessary. Replace
stem (6) and gasket (14).
Valves
4.2 Liquid Injection Valve
39