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MAINTENANCE - See Figure 4
WARNING: USE CARE WHEN
DISASSEMBLING, SPRING FORCES PRESENT.
CAUTION: Do not subject O-rings, gasket, or
diaphragms to cleaning fluid, acetone, or any
halogenated hydrocarbons such as degrease liquids,
etc. Clean only with a soft, dry cloth. Metal parts can
be cleaned with a suitable solvent, and then dried
thoroughly before reassembly.
NOTE: Threads on screw (detail 8), diaphragm clamps,
spring housing screws (detail 11), bushing, and pressure
assembly screws (detail 21 should have Loctite Sealant
"H" or equivalent applied before reassembly. See * below.
Pressure Assembly
Remove four screws (detail 21) and O-ring (detail 22).
Replace defective pressure assembly, reassemble* and
recalibrate.
Bushing
To replace bushing O-ring (detail 19), remove bushing
and replace defective O-ring. Reassemble* unit and replace
in housing assembly. Recalibrate differential if unit is an
automatic reset model.
Housing Assembly and Stem
Remove cap screw and turn adjustment screw (detail 6)
counterclockwise to bring the range spring to free length.
Remove the four screws (detail 11), spring housing, spring
seat (detail 4), range spring and gasket. Remove the
pressure assembly as previously described. As applicable,
proceed with the Direct- or Reverse-Acting instructions
below.
Direct-Acting
Prevent the spring seat (detail 9) from rotating and back
the lock nut away (counterclockwise) from the nut several
turns. Preventing the spring seat (detail 9) from rotating,
remove the adjusting screw, nut, and lower flange.
Prevent the spring seat (detail 9) from rotating and
remove the exposed diaphragm clamp. Remove the
exposed diaphragm. Remove the stem by pulling the flange
from the valve housing.
To replace O-ring (detail 31) on stem, prevent spring
seat (detail 9) from rotating and remove screw (detail 8).
Prevent stem from rotating and remove spring seat (detail
9) and flange. Proceed with instructions designated Direct-
and Reverse-Acting below.
Reverse-Acting
Prevent the nut from rotating and remove the screw
(detail 8) and spring seat (detail 9). Remove the upper
flange.
Prevent the nut from rotating and remove the exposed
diaphragm clamp. Remove the exposed diaphragm. Remove
the stem by pulling the remaining flange from the valve
housing.
To replace O-ring (detail 31) on stem, prevent the nut
from
rotating
and
(counterclockwise) from the nut several turns. Remove the
adjusting screw, nut, and flange. Proceed with instructions
designated Direct and Reverse-Acting below.
back
the
lock
nut
Direct- and Reverse-Acting
Remove remaining diaphragm clamp and diaphragm.
Remove retaining ring (detail 32,), spring (detail 34), and
sleeve. Remove defective O-ring (detail 31) and replace.
Reassemble sleeve, spring (detail 34) and retaining ring
(detail 32).
To replace O-ring (detail 29) in valve housing, remove
retaining ring (detail 28) and defective O-ring (detail 29).
Replace O-ring, then retaining ring.
To replace O-ring (detail 30) which seats against the
sleeve, remove the defective O-ring with a knife or other
sharp-pointed tool. Carefully remove any residue and clean
area from where O-ring was removed with a suitable
solvent. Dry thoroughly. Place a few drops of liquid Viton
(Pelmor Laboratories' PLV-2000 or equivalent) on the
seating area just cleaned. Take the replacement O-ring,
remove from it any dust, dirt or foreign matter, and bond it
to its seating area. Allow to cure for one or more hours.
With all O-rings, diaphragms, gaskets and defective
parts replaced, reassemble as follows:
On models with automatic reset, turn differential
adjustment screw into bushing clockwise until small end of
bellows head is even with surface "D" - see Figure 3. (On
models with manual reset, the reset plunger will need to be
held depressed to obtain surface "D" contact as explained
below).
Replace stem, diaphragms, and diaphragm clamps*.
Tighten clamps hand
a
wrench,
Reassemble* remaining parts as shown in figure 3.
On models with manual reset, depress the reset plunger
to maintain small end of bellows head with surface "D"
contact while obtaining the following dimensions - see
figure 3.
Apply approximately one pound force (4.45 N) by finger
at point "P." Turn spring seat to obtain dimension "A" - see
Table 3. Lock spring seat in place with screw*.
With a gage in place to hold dimension "A," adjust
adjusting screw to dimension "B" and nut to dimension "C"
- see Table 3. Lock both in place with lock nut as shown in
figure 3.
Release reset plunger on manual reset models and turn
differential
approximately 3/4 turn on auto reset models.
Reassemble* remaining parts and recalibrate sensor.
FIELD REVERSAL
To change the sensor from direct- to reverse-acting or
vice versa, remove the spring seat (detail 9), adjusting
screw, and nut from stem. Reset bellows head to surface
"D" as explained in the Housing Assembly and Stem
Maintenance section. Reassemble spring seat (detail 9),
adjusting screw, and nut on appropriate end of stem using
figure 3 as a guide. Reset dimensions "A," "B" and "C" and
reassemble as explained in the Housing Assembly and Stem
Maintenance
assembled.
away
5
tight
. While holding each clamp with
tighten
approximately
adjustment
screw
instructions.
Recalibrate
1/4
turn
more.
counterclockwise
sensor
when
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