Fisher EHD series Instruction Manual page 9

Instruction Manual
D100392X012
injury. Use a stick or other device to thread a rope or sling through the windows. Use this rigging to secure the cage to the
bonnet or hoist to prevent damage or injury should the cage suddenly separate from the bonnet.
CAUTION
When lifting the bonnet (key 1), be sure that the valve plug and stem assembly (keys 3 and 4, figure 12 or 14) remains on
the seat ring (key 6, figure 12 or 14). This avoids damage to the seating surfaces as a result of the assembly dropping from
the bonnet after being lifted part way out. The parts are also easier to handle separately.
4. Remove the hex nuts (key 14, figure 12 or 14) and washers (key 29 and 33, figure 12, 13, or 14). Carefully lift the
bonnet off the valve plug stem. If the valve plug assembly starts to lift with the bonnet, use a brass or similar
hammer to tap the end of the stem and tap it back down. Set the bonnet on a protective surface to prevent damage
to the bonnet gasket surface.
CAUTION
Use care to avoid damaging gasket sealing surfaces.
EHD piston rings (key 8) are brittle and in two halves. Use care to avoid damage to the piston rings caused by dropping or
rough handling.
5. Lift the plug assembly (keys 3 and 4, figure 12 or 14) out of the valve body.
6. To remove the cage (key 2, figure 12 or 14), if it remained in the valve body, install eyebolts or similar devices into
the 1/2 inch 13‐UNC tapped holes in the top of the cage. Using the eyebolts, carefully lift the cage out of the valve
body. Remove the top and bottom cage gaskets (key 11, figure 12 or 14). Carefully remove any residual silver or tin
from the gasket surfaces.
7. Cover the opening in the valve body to protect the gasket surface and to prevent foreign material from getting into
the valve body cavity.
Table 6. Body‐to‐Bonnet Bolting Torques
VALVE SIZE
NPS
8, 10
12, 14
8. Remove the packing flange nuts, packing flange, upper wiper and packing follower. Carefully push out all the
remaining packing parts from the valve side of the bonnet using a rounded rod or other tool that will not scratch the
packing box wall. Clean the packing box and these metal packing parts shown in the figure 4 arrangements: packing
box ring, spring, lantern ring, washer if used, and packing follower (keys 11, 8, 10, and 13).
9. Inspect the valve plug stem threads for any sharp edges that might cut the packing. Use a whetstone or emery cloth
to smooth the threads if necessary.
10. Remove the protective covering from the valve body cavity, and install the cage using new cage gaskets (key 11,
figure 12 or 14).
11. Install the plug and stem assembly. Be sure the seal ring or piston rings are installed correctly as described under
Trim Replacement.
B7, B16, BD, 660 STUDS
VALVE
RATING
NSm
CL1500 2710
CL2500 4070
CL1500 8130
CL2500 5830
EH Valves NPS 8 through 14
lbfSft NSm
2000 2035
3000 3050
6000 6100
4300 4370
June 2017
B8, B8M STUDS
lbfSft
1500
2250
4500
3225
9