Hermetic Sealing Of The Sampling System; Sampling Sensor; Sampling Hose - Bosch ETT 008.71 Instructions D'emploi

7. Maintenance
Routine maintenance will ensure that the unit is ready for ope-
ration.
The following periods must be observed, unless the regulatory
authority specifies otherwise.
● Every six months
- Replace the coarse filter GF1 (7) in sampling hose.
- Replace the intake filter GF2 (4) (see Section 7.4.4).
- Check whether all three PVC hoses are connected to the gas
outlets (10/11/121)
- Visual inspection of the sampling sensor (9)
- Leak test in accordance with section 5.2
● Annual maintenance
This maintenance must be carried out by a qualified service
agency. It comprises six-monthly maintenance and the following
additional points:
- Checking the measurement accuracy of the analyser with a test
gas
- Replacing the activated charcoal filter (2) in the zero gas path
- Replacing the protective pump filters GF3 (3) and GF4 (1) (see
Section 7.4.4).
The calibration requirements of the responsible (local) authority
must be observed.
7.1

Hermetic sealing of the sampling system

A hermetically sealed sampling system is an absolute necessity
for accurate exhaust analysis. Testing it for leaks every day is
recommended (see section 5.2).
7.2

Sampling sensor

Keep the aperture at the tip of the sensor clean. If any conden-
sation or HC residue is present, remove the sampling sensor
from the hose and blow it out with compressed air against the
direction of intake.
7.3

Sampling hose

Check for damage. If any HC residue or condensation is present,
pull the hose off the analyser and blow it out with compressed air
against the direction of intake.
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7.4 Coarse filter
! Only use genuine filters part number 1 687 432 005 when
replacing GF1, GF2, GF3 and GF4 filters.
If other brands or types (e.g. commercially available fuel filters),
the measuring chambers downstream will be damaged by cor-
rosion residues (particles of rust from metal filter cartridges) and
inadequate filtering.
All claims made under warranty or for goodwill will be rejected if
failure is found to have been caused by use of the wrong filters.
The exhaust gas to be measured is cleaned of particles and ea-
rosols via a cascade of filters.
Particles are solid items such as dust and soot. Aerosols are tiny
droplets of liquid. These may be deposited in the gas conduit
and the analysis chamber4 to form coatings which lead to the
error messages Err 3 and Err 4. For avoiding the damages to
the exhaust-gas analyser, attention must be paid to ensure that
the correct type of filtering is used and the filters are changed as
required.
7.4.1 GF1 filter
This filter removes large particles from the gas flow and must
therefore be replaced the most frequently.
Depending on how often the exhaust-gas analyser is used, replace
the filter approx. once a week.
If very dirty (fault message for no flow), replace the coarse filter.
The same applies if HC residue is present.
7.4.2 GF2 inlet filter
The second filter removes other particles and aerosols from the
gas flow. The dirtier this filter is, the smaller the pore size and there-
fore the better the filtration. The filter becomes wet very quickly due
to the water in the exhaust gas. This moisture washes the aerosols
out of the gas flow and improves filtration of the particles.
i A wet filter is therefore desirable!
Depending on how often the exhaust-gas analyser is used, replace
the filter approx. once a month to once a year.
If very dirty (fault message for no flow), replace the coarse filter.
The same applies if HC residue is present.
! Connecting pieces (31) are not to be removed from the rear
panel!