Land 4500 MKII Premier, Operation And Maintenance Manual

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Model 4500 Premier Dust and Opacity Monitor
128
Changing the pathlength
The Model 4500 Premier has been configured and tested for the pathlength specified at the time of
purchase. Changing its pathlength will alter its calibration and may invalidate any certificate of compliance.
Do not change the installation pathlength without authorization from Land Instruments International.
Tools required
2.5 mm hex (Allen) key
5 mm hex (Allen) key - supplied
Set the correct focus
1.
Open the transceiver housing by undoing the two quick-release clamps.
2. Undo the two socket headed, captive screws holding the zero-point assembly and carefully
remove it. Mark the top of the lens assembly.
3. Undo the 3 M4 socket headed screws holding the lens assembly. NB These screws are NOT
captive.
4. Carefully remove the lens assembly, taking care not to touch the lens surface.
5. Remove the o-ring from the lens and remove the focus spacers. There are 3 spacers, with
thicknesses 2 mm, 4 mm and 8 mm. Select the appropriate spacers to give the correct focus
distance for the flange-to-flange pathlength shown in the table.
6. Replace the O-ring on the lens assembly.
7. Select the correct length of M3 fixing screws for the flange-to-flange pathlength shown in the
table. Carefully place the screws into the holes in the lens assembly, making sure that they
pass through the holes in the focus spacers.
8. Slide the lens assembly into place. Ensureing the orientation is the same as when removed.
9. Fasten all of the screws using a 2.5 mm hex (Allen) key.
10. Replace the zero-point assembly.
11. Close the housing and fasten the quick-release clamps.
Fit the correct retroreflector.
1.
Open the retroreflector housing by undoing the two quick-release clamps.
2. Undo the two M3 socket headed screws holding the retroreflector assembly and carefully
remove it. NB These screws are NOT captive.
3. Select the correct retroreflector for the flange-to-flange pathlength shown in the table. Fit the
retroreflector using the M3 socket-head screws.
4. Close the housing and fasten the quick-release clamps.
Perform a clear stack calibration at the new pathlength – see B3-3