Replacing The Loader Range Spring, Diaphragm Assembly, Ball Seat, Tubing, And Ball; Replacing The Loader Valve Plug And Valve Plug Spring - Fisher 4194B Series Instruction Manual

4194A, B, and C Series
21. Drive in the groove pin (key 303) to hold the
switch lever.
22. Replace the lever cover plate (key 305), and at-
tach with two screws (key 288).
23. Perform the Assembly procedure in the Replacing
the Auto/Manual Station section.
Replacing the Loader Range Spring,
Diaphragm Assembly, Ball Seat, Tubing,
and Ball
Refer to figure 5-27 for key number location.
Disassembly
1. Remove the auto/manual station from the controller
as described in steps 1 through 4 of the replacing the
auto/manual station procedure.
2. Remove the tubing assembly (key 309).
WARNING
To avoid personal injury caused by pre-
load from the range spring (key 283),
turn the loader knob (key 287) counter-
clockwise (opposite to the arrow) to re-
lieve pressure on the spring.
3. Loosen the four screws (key 289), and separate
the upper loader assembly (key 282) and the lower
loader assembly (key 274).
4. Remove the loader range spring (key 283), range
spring cup (key 284), and diaphragm assembly (key
281).
5. Remove the tube (key 278), ball seats (key 280)
and ball (key 279).
Assembly
6. Turn the loader knob (key 287) counterclockwise to
back the spring adjustment screw (key 285) all the
way out to eliminate loading the range spring.
7. Position the range spring cup (key 284), the range
spring (key 283), and the diaphragm assembly (key
281) on the upper loader assembly (key 282).
8. Position the ball (key 279), the tube (key 278), and
the ball seats (key 280) between the ears of the loader
assemblies (keys 282 and 274); position the dia-
5–32
phragm assembly (key 281) between the main halves
of the loader assemblies.
The tube (key 278) must be well seated
in the cups of the ball seats (key 280).
9. Bolt the loader assembly halves together using the
four screws (key 289).
CAUTION
Be sure that the supply and exhaust
seats of the loader are correctly aligned.
Misalignment will impair loader perfor-
mance.
10. Attach the tubing assembly (key 309).
11. Perform the assembly procedures in the replacing
the auto/manual station section.
Replacing the Loader Valve Plug and
Valve Plug Spring
Refer to figure 5-27 for key number location.
1. Remove the controller assembly from the case by
performing steps 1 through 3 of the case and cover
replacement procedures.
2. Loosen the spring seat screw (key 275).
3. Remove the valve plug spring (key 276) and the
valve plug (key 277).
4. Inspect the parts, and replace as necessary.
5. Install the valve plug spring and valve plug.
6. Tighten the spring seat screw.
7. Temporarily apply supply pressure and process
differential pressure and check for leaks.
8. Position the controller assembly in the case and
start, but do not tighten the nine mounting screws.
Slide the controller assembly down to assure an O-
ring seal at the pressure connections along the bottom
of the case. Hold the controller assembly in place
while tightening the nine mounting screws.
9. Mount the controller as described in the Installation
section.
10. Connect external piping to the controller.
Note