35
PFP7/REV C/01-08
Section 9
Component replacement
9.1
Chimney and optical components
9.1.1
Mixing chamber dismantling
Figure 9.1.1
: Mixing chamber, nebuliser and burner assembly.
1. Ensure power, fuel and air supplies to the instrument are disconnected.
2. Remove the nebuliser (1) by turning the retaining cam and withdrawing the nebuliser
from the mixing chamber end cap (2). Unscrew the air inlet tube (3) from the nebuliser
and place it safely to one side. Pull the fuel inlet tube (4) and drain tube (5) from their
connectors on the mixing chamber end cap.
3. If the instrument has been running with the flame alight, allow 30 minutes for the burner
system to cool down. When it is cool the knurled brass ring (6) may be unscrewed and
the mixing chamber (7) lowered from the chimney and removed.
4. The burner (8) can be withdrawn from the burner tube (9) and the end cap removed by
releasing the three socket head screws (10). The impact bead and impeller assembly
(11) can be removed by releasing the centre pozidriv screw (12) in the rear plate (13) of
the mixing chamber. The rear plate can be removed by releasing the three outer
pozidriv screws (14).
5. All items should be inspected for damage and contamination before cleaning and re-
assembly. Re-assembly is the reverse of dismantling and the end cap and rear plate
retaining screws must be securely tightened to give gas tight seals.
6. Ensure that when re-assembling the mixing chamber that the baffles are positioned at
45 degrees to each other, as shown in Figure 9.1.2.
8
6
1
2
(3)
(4)
(5)
7
9
10
12
14
11
13
8
6
1
2
(3)
(4)
(5)
7
9
10
12
14
11
8
6
1
2
(3)
(4)
(5)
7
9
10
12
14
8
6
1
2
(3)
(4)
(5)
7
9
10
12
14
11
13