Fisher EHD series, Инструкция по эксплуатации, Страница: 21 / 32

Instruction Manual
D100392X012
EH Valves NPS 8 through 14
June 2017
21
D
The open interior of the Bore Seal plug seal must face up in a valve with flow‐up construction (figure 5).
D
The open interior of the Bore Seal plug seal must face down in a valve with flow‐down construction (figure 5).
Figure 9. Lower (Valve Plug to Seat Ring) and Upper (Bore Seal Plug Seal to Cage) Seating Surfaces
NOTE:
UPPER SEATING SURFACE IS THE AREA OF CONTACT BETWEEN THE
BORE SEAL METAL PLUG SEAL AND THE CAGE.
PLUG
CAGE
SEAT
RING
UPPER SEATING SURFACE
LOWER SEATING SURFACE
A6780
1
1
PISTON
RING
RETAINER
CAGE
BORE SEAL
PLUG
SEATING AREA
3. Place the Bore Seal plug seal over the top of the valve plug. The retainer will help guide the Bore Seal down onto the
plug. Do not force the Bore Seal over the plug. For flow down constructions, skip to step 5.
4. An installation tool (see table 8) must be inserted into the Bore Seal prior to using the retainer to guide it down the
plug.
5. Apply a suitable high‐temperature lubricant to the threads on the plug. Then, place the Bore Seal retainer onto the
plug and tighten the retainer using an appropriate tool such as a strap wrench. For flow down constructions, skip to
step 7.
6. Remove the retainer and then the installation tool. Place the Bore Seal retainer back onto the plug and tighten the
retainer using an appropriate tool such as a strap wrench.
7. Using an appropriate tool such as a center punch, stake the threads on top of the plug in one place (figure 7) to
secure the Bore Seal retainer.
8. Replace the piston ring(s) following instructions in the Trim Replacement section of this manual.
9. Return the seat ring, cage, plug/retainer assembly, and stem to the valve body and completely reassemble the valve
package following the appropriate instructions in the Trim Replacement section of this manual.
CAUTION
To avoid excessive leakage and seat erosion, the valve plug must be initially seated with sufficient force to overcome the
resistance of the Bore Seal plug seal and contact the seat ring. You can correctly seat the valve plug by using the same force
calculated for full load when sizing your actuator. With no pressure drop across the valve, this force will adequately drive
the valve plug to the seat ring, thus giving the Bore Seal plug seal a predetermined permanent set. Once this is done, the
plug/retainer assembly, the cage, and the seat ring become a matched set.
With full actuator force applied and the valve plug fully seated, align the actuator travel indicator scale with the lower end
of valve travel. Refer to the appropriate actuator instruction manual for information on this procedure.