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Maintenance & Fault Finding 3098 Technical Manual
5-8
5.2.4 Re-assembly Procedure
1. Invert the 3098 so that the diaphragm counter-bore faces upwards.
2. Locate the diaphragm assembly into the counter-bore housed in the welded assembly - not the base plate.
3. Carefully replace the base plate over the diaphragm, making sure that the diaphragm is not moved from its central
position in the counter-bore and that the connectors line up for the two ‘base to top plate’ gas pipelines.
4. Place the bolts into their counter-bores and tighten them in ascending order as shown in the diagram below:
1
3
5
2
4
6
5. Replace the two ‘base to top plate’ gas pipelines and the density meter (if it has been removed) and perform a leak
check on all seals described in section 5.2.7.
6. The 3098 can now be replaced in the main enclosure, by reversing the procedure described for ‘Main meter (3098)
removal’.
5.2.5 3098 Filter Change Procedure
1. Remove unit from installation and enclosure as described in sections 5.2.1 above.
2. Place the unit on its side and loosen the fittings that retain the input gas interconnection pipe.
3. Once this pipe has been removed, loosen and remove the filter fitting that screws into the unit base plate.
4. The filter element cannot be removed from its housing, so the complete fitting must be changed.
5. The new filter should be inserted into the base plate, using PTFE tape to produce a gas tight seal. Care should be
taken to ensure that no stray parts of PTFE tape fall into the instrument.
6. Re-assembly is the reverse of points 2 and 1 above.
Note: Once the unit has been replaced into its enclosure, a leak check must be performed before on-line operation.