Fisher 4194B Series Instruction Manual page 40

4194A, B, and C Series
12. Remove the retaining clip (key 26).
13. Remove the proportional band adjustment knob
(key 25) and Mylar washer from the set point beam
assembly (key 23).
14. Inspect the nozzle assembly (key 21), and replace
it if necessary. Inspect the nozzle orifice, and clean it,
if necessary. Also, inspect the Mylar washers, and re-
place them if necessary.
15. Inspect the nozzle assembly O-ring (key 24) and
replace it, if necessary.
Assembly
16. Apply a suitable lubricant, such as key 318 or
equivalent, to the set point beam assembly; then posi-
tion a Mylar washer (key 22) and the proportional band
adjustment knob (key 25) on the set point beam as-
sembly (key 23) as shown in figure 5-3.
17. Position the retaining clip (key 26) on the three
posts of the proportional band adjustment knob.
18. Place the second Mylar washer on the nozzle as-
sembly. Apply a suitable lubricant, such as key 317 or
equivalent, to the nozzle assembly O-ring.
19. Insert the nozzle assembly (key 21) through the
set point beam assembly (key 23), the Mylar washer
(key 22), the proportional band adjustment knob (key
25) and the retaining clip (key 26) into the cap. Align
the nozzle with the tab on the proportional band ad-
justment knob shown in figure 5-4; make sure the pro-
portional band adjustment knob engages the flats on
the nozzle assembly.
20. While holding the nozzle assembly (key 21)
against the set point beam assembly (key 23), de-
press the retaining clip (key 26), and install the E-ring
(key 27) into the E-ring groove on the nozzle assembly
(key 18). Ensure that all three tabs of the E-ring are
engaged.
21. Inspect the O-ring on the relay nozzle tubing as-
sembly (key 18) and replace it, if necessary. Apply a
suitable lubricant to the O-ring.
22. Install the relay nozzle tubing assembly (key 18)
into the set point beam assembly.
23. Set the proportional band adjustment between
DIRECT and REVERSE. Do this by aligning the tab on
the proportional band adjustment knob with the hole in
the set point beam assembly as shown in figure 5-4.
24. Position the proportional band adjustment knob,
relay nozzle tubing assembly and the set point beam
assembly on the frame. Screw the relay nozzle tubing
nut loosely into the frame manifold.
25. Insert the machine screw, with plain washer (keys
19 and 20), through the frame and start it into the relay
nozzle tubing assembly (key 18), but do not tighten.
5–8
TAB
HOLE
W3761 / IL
Figure 5-4. Proportional Band Adjustment Knob Setting
FLAPPER
W3449 / IL
Figure 5-5. Nozzle-Flapper Positioning
26. Center the nozzle on the flapper as shown in fig-
ure 5-5 while squeezing the set point beam assembly
NOZZLE