DURAG D-R 290, Operating Manual

Page: 163 / 202

8 | Maintenance
D-R 290 163
The control cycle, irrespective of whether it is started automatically or manually,
always ends automatically once the cycle has been completed.
All other functions (zero point check, reference point check, contamination check,
linearity check) remain active until either they are terminated or another function is
started.
Functional test of the fail-safe shutter
Maintenance and the functional test on the fail-safe shutter should be carried out at
the maintenance interval for the measuring instrument, depending on the dust or soot
content of the measuring gases.
For checking for deposits in the guide slot of the fail-safe shutter, and for removal of
those deposits the protective device including the measuring head or reflector must be
dismantled.
To avoid unnecessary downtime this can be scheduled to be done in the course of
plant inspection.
WARNING Risk of injury due to crushing and abrasion!
Do not insert fingers into the closing area of the fail-safe shutter. Before maintenance
work, disconnect terminals 16 and 17 in the DSK AE control electronics. To do this,
unplug the connection plug at the measuring head for the fail-safe shutter. (When
disconnected, the fail-safe shutter is closed).
1. Where disassembly of the device from the measuring site is necessary, undo the
connections:
∙ between the measuring head and control unit
∙ between the fail-safe shutters and control device for the fail-safe shutters
(including the connecting cables to the measuring head).
2. By undoing the quick-release clamps, release the measuring head or reflector from
the purge air flange.
3. If necessary, disconnect the measuring head or reflector as from the purge air sup­
ply.
4. Pull the rubber sleeve from the space in the D‑SK 290 MA fail-safe shutter and the
purge air flange over the purge air flange.
5. Undo the self-locking nuts and take the spherical washers off the threaded studs.
6. Detach the purge air flange for the measuring head or reflector from the threaded
bolts.
7. Take the disc springs off the threaded bolts on the flange tube.
8. Carefully release the D‑SK 290 MA fail-safe shutter from the welded-in flanged
tube, and remove it. Make sure that the flat seal in front of the flange tube is not
damaged. Damaged seals must be replaced immediately.
9. Checking for deposits in the guide slot of the fail-safe shutter, and remove them if
necessary. Dirt can be removed using oil-free compressed air, a brush or cloth and
cleaning agents that dry without leaving any residue (e.g. dishwashing liquid). Do
not under any circumstances use solvents that attack aluminium.
10. Reinstall the measuring head or reflector, and reconnect the purge air supply.
●
Test the fail-safe shutter with the test function:
8.2.11
Checking for
deposits
Testing the fail-safe
shutter