Fisher NPS 12 Instruction Manual page 9

Instruction Manual
D103553X012
Figure 3. Typical Packing (Continued)
PACKING
FOLLOWER
(KEY 13)
GRAPHITE RIBBON
PACKING RING (KEY 7)
GRAPHITE FILAMENT
PACKING RING (KEY 7)
LANTERN RING
(KEY 8)
PACKING BOX
RING (KEY 11)
31.8 and 50.8 mm
(1-1/4 and 2 INCH) STEM
SINGLE ARRANGEMENT
GRAPHITE RIBBON/FILAMENT PACKING
NOTE:
0.102 mm (0.004 INCH) THICK SACRIFICIAL ZINC WASHERS:
USE ONLY ONE BELOW EACH GRAPHITE RIBBON RING.
A6060
CAUTION
Avoid damage to the seating surfaces caused by the valve plug and stem assembly dropping from the bonnet after being
lifted part way out.
When lifting the bonnet (key 1, figure 4), either be sure that the valve plug and stem assembly remains in the valve and on
the seat or, temporarily install a valve stem locknut on the valve stem. This locknut will prevent the valve plug and stem
assembly from dropping out of the bonnet.
WARNING
To avoid personal injury or property damage caused by uncontrolled movement of the bonnet, loosen the bonnet by
following the instructions in the next step. Do not remove a stuck bonnet by pulling on it with equipment that can stretch
or store energy in any other manner. The sudden release of stored energy can cause uncontrolled movement of the bonnet.
If the cage sticks to the bonnet, proceed carefully with bonnet removal.
Note
The following step also provides additional assurance that the valve body fluid pressure has been relieved.
4. Hex nuts (key 16, figures 5 or 6) attach the bonnet to the valve body. Loosen these nuts or cap screws
approximately 3 mm (1/8 inch). Then loosen the body-to-bonnet gasketed joint by either rocking the bonnet or
prying between the bonnet and valve body. Work the prying tool around the bonnet until the bonnet loosens. If no
fluid leaks from the joint, remove the nuts completely and carefully lift the bonnet (key 1, figure 4).
5. Set the bonnet on a protective surface to prevent damage to the bonnet gasket surface.
6. Whenever the bonnet has been removed, replace the bonnet gasket and the cage gasket (keys 10 and 11, figures 5
and 6). Remove the bonnet gasket.
PACKING
FOLLOWER
(KEY 13)
GRAPHITE RIBBON
PACKING RING (KEY 7)
GRAPHITE FILAMENT
PACKING RING (KEY 7)
LANTERN RING
(KEY 8)
PACKING BOX
RING (KEY 11)
31.8 and 50.8 mm
(1-1/4 and 2 INCH) STEM
DOUBLE ARRANGEMENT
Large ET and ED Valves
July 2014
9