Groth 1660A - Manual (Page 9)

Page 9 of 16
FILM SEAT PALLET
Turn the pallet assembly upside down to
disassemble. If placing in a vise, clamp
against the flats on the swivel ball [24]. Do
not clamp on the socket or it will be deformed
and restrict seat alignment. Loosen the jam
nut [34] and turn the jackscrew [33]
counterclockwise to release tension on the
FEP film [40]. Use an allen wrench to hold the
countersunk screws [42] and loosen the hex
nuts [43] that retain the ring [41]. Remove all
components from the jackscrew assembly
(see Figure 4) and replace the film. Remove
the retaining ring [28] and replace the O-Ring
[29].
To assemble, install the O-Ring [29] in the
pallet counterbore and insert the swivel socket
[26]. Replace the retaining ring [28]. Do not
expand the retaining ring excessively.
Table 6
FEP Seat Film Dimensions
SIZE O.D. HOLE DIA.
2” 4.50” 0.38”
3” 5.50” 0.38”
4” 6.50” 0.38”
6” 8.50” 0.44”
8” 10.63” 0.44”
10” 12.63” 0.62”
12” 14.63” 0.62”
The FEP film [40] is provided at least 3/4”
larger than the outside diameter of the film
seat ring [41]. This excess material is
required for handling at assembly. Place the
film on a clean flat surface and punch a hole
in the center (see Table 6) to provide
clearance for the jackscrew bushing [35].
Install the jackscrew bushing [35] through the
film tension plate [39]; as shown in Figure 4.
Lay the film [40] over the plate [39], then the
fluoropolymer washer [46]; flat washer [38];
belleville washer [37]; and tighten the jam nut
[36] while holding the jackscrew bushing with
a wrench. Tighten until the belleville washer
is flat; do not over-tighten as the FEP film can
be damaged or cut at the washer O.D. Use
care in handling the film at all stages of
assembly.
Screw the jam nut [34] completely onto to the
jackscrew [33] and thread the jack screw into
the jackscrew bushing [35] until the tip
extends slightly through the opposite end (hex
side).
Figure 4: Film Pallet Assembly
Position the film sub-assembly on the face of
the pallet with the tip of the jackscrew [33] in
the counterbore of the swivel socket [26].
Hold the film so it is taut and wrinkle free.
Align the bolt holes of the seat ring [41] and
pallet [45] and press the parts firmly together,
clamping the film securely.
Punch four holes at 90
 apart through the film
and insert the socket head screws [42]
through the ring and plate. Install the lock
washers [44] and hex nuts [43] and tighten
using an allen wrench to hold the screws.
Complete the assembly by punching the
remaining holes and install the screws, lock
washers and hex nuts.
After all fasteners are tightened, turn the
jackscrew [33] clockwise to tighten the film
until the slope is approximately 15
. Do not
over-tighten, as it is possible to bend the
tension plate [39] or tear the film. Tighten the
jam nut [34] to lock the jackscrew. Using a
sharp knife, trim the excess film at the O.D. of
the ring [41].
Carefully set the film seat pallet assembly
onto the valve body seat. Check the gap
between the bottom of the film seat ring [41]
and the top surface of the body seat; it should
be between 1/32” and 1/16”. If there is
insufficient clearance, the film should be
retensioned. Carefully lift the assembly out of
the valve and loosen the jam nut [34] on the
jackscrew two or three turns. Rotate
jackscrew clockwise as required to tension
film and then retighten the jam nut [34].
Lower the pallet assembly into the valve and