30
3.2.3 69BBlocked paper filters
The paper filters are small so that they are frequently forgotten or neglected,
although they can block the flow when they are not replaced for long.
3.2.4
70BBlocked lance hole over the crucible
The hole in the ceramic heat shield over the crucible can be restricted or blocked.
Clean by using the brass brush as described in the operation manual. If this may
not be enough then clean the hole by using a piece of wire or a pipe cleaner.
3.2.5
71BBlocked furnace outlet
Unscrew the cap-nut at the furnace outlet and remove the plastic tube. Pass thru
the fitting a pipe cleaner. Open the furnace in order to be sure that the pipe cleaner
has passed thru the fitting reaching the furnace area.
Completely remove the plastic tube by unscrewing the left hand cap-nut on the
dust filter assembly. Clean this fitting the same way like before. If necessary clean
the plastic tube as well.
3.2.6
72BToo low oxygen pressure
Check the oxygen gauge. The reading should be 1.5 bar (22.5psi). If the pressure
is too low, it can be adjusted by pulling and turning clockwise the knob of the
pressure regulator on the rear panel of the analyzer. It is placed on the right hand
side close to the generator blower and the knob is accessible from inside the
analyzer. An adjustment is possible provided that there is sufficient pressure at the
input of this pressure regulator.
If the input pressure is too low, check the (external) pressure gauge of the oxygen
supply (cylinder). The input oxygen pressure to the analyzer should be between 4
and 6 bar (60 to 90 psi).
3.2.7
73BOutlet tap of the oxygen regulator is not properly open
It is not necessarily enough to have sufficient oxygen flow if only the right pressure
is adjusted on the oxygen regulator of the bottle/cylinder. It is equally important to
properly open the small tap at the outlet of the pressure regulator. If this outlet tap
of the regulator is not properly open, you may have enough pressure at the
analyzer when there is no or little oxygen demand. But when the oxygen demand
grows, for example at the beginning of combustion when the sample needs a lot of
oxygen to burn, the pressure may drop to a very low level if not enough oxygen
can be supplied to the analyzer at the moment of high oxygen demand. The same
problem will appear during furnace purging before or after the analysis, depending
on the actual settings in the software.
3.2.8
74BContaminated or corroded solenoid valve
In case of steel analysis it is very unlikely to have problems with valves. In case of
exceptional materials like ores, solenoid valves can be contaminated up to the
extent of failing. This depends mainly on the amount of sulfur and moisture in the
sample. The most affected valves are the outflow valve V1 and the bypass valve
V4. The valves can be cleaned. If cleaning may not help, they should be replaced.
For extremely contaminating resp. corroding samples, we have currently valves
under evaluation, where the carrier gas does not get in contact with any metal
parts but only with chemically resistant plastic.
3.2.9
75BFaulty oxygen regulator
A faulty oxygen regulator can of course cause a similar problem when it does not
keep the pressure level at moments of higher oxygen consumption.
3.2.10
76BBent plastic tube of oxygen supply
When the plastic tube supplying oxygen from the bottle to the analyzer is bent,
there will be the same problem like described in the above two subjects. There will
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