Diagnosis and maintenance
The following factors have an influence on the mainte-
nance frequency:
n
Sample properties (with/without sliding properties,
corrosive, dusty).
n
Vaporization temperature
n
Ambient temperature
n
Sample pressure
A service life of one year is possible depending on the
sample properties and the duration of the analysis.
IMPORTANT
To achieve a long service life, the actual
state must be assessed as exactly as possi-
ble during the first maintenance operation!
We recommend preventative maintenance
every six weeks!
Sample residues
If, during permanent operation, products are injected
which contain non-volatile or easily polymerized com-
ponents (salts, proteins, monomers etc.), these compo-
nents may be deposited in the vaporizer, in the injection
hole and on the injection tappet. It is necessary to occa-
sionally clean the vaporizer and the injection tappet de-
pending on the concentration of these components in
the sample and on the frequency with which such sam-
ples are injected.
If the surface of the injection tappet is attacked and
roughened by the sample, it must be replaced by a tap-
pet made of a different material (e.g. Hastelloy, Monel,
tantalum, sapphire, ZrO
2
).
The service life is greatly reduced if:
n
The sample is corrosive
n
The sample contains particles
n
Salts are dissolved in the sample or if the sample
contains materials which are not vaporized.
The service life is reduced normally:
n
At a high vaporization temperature (gasket becomes
malleable)
n
With gaskets with a 25% glass filling
n
At a high sample pressure (>20 bar)
n
With non-volatile samples of high boiling point
Lenticular gaskets
The sample flow unit can become blocked or is subject
to wear by particles in the sample.
n
The glass fibers of the filling project out of the pro-
cessed surface, resulting in a low wear effect on the
tappet. Pure Teflon and Rulon do not have this prob-
lem, but are not suitable for all applications.
n
If gaskets are used outside their temperature class,
they are either too hard or too soft. This results in a
reduced service life because the malleability is too
low or too high.
Pneumatic drive
The silicone O-rings of the pneumatic drive close de-
pending on the injection frequency and the ambient
temperature. They should therefore be regularly
greased with Dow Corning Grease 111.
2-IV Register8.vp Stand: 20.11.2000
Liquid injection valve
1
21
43
5
22
7
91
9
2
3
6
11
23
23
4
42/41
11
32
31
92
93
Liquid injection valve
1 Control cylinder
11 Hexagon screw
2 Control piston
21 Guide pin
22 Injection tappet
23 O-ring, large
3 Valve body
31 Label for dosing volume
32 O-ring, small
4 Adjustment assembly with nut (41) and conternut (42)
43 Plate springs (8 off)
5 Sample flow unit
6 Lenticular gaskets
7 Vaporizer
8 Flange
9 Heating mushroom
91 Heating cartridge
92 Temperatur sensor
93 Safety temperature limiter
8
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