Data Sheet

EU Valve
D102004X012
Product Bulletin
51.1:EU
September 2014
4
Figure 2. Typical Fisher EUD with Bore Seal
W6022-2
PLUG
RETAINER
BORE SEAL
PISTON RING
CAGE
RETAINER
CAGE
BORE SEAL
PLUG
SEATING AREA
PISTON RING
SEATING AREA
VIEW A
A
FLOW DOWN
FLOW UP
Bore Seal Description
TheBoreSeal(figure2)isavailablefortheEUDand
EWD only and is required for Class V shutoff
applications where the service temperature exceeds
316_C(600_F). For service temperatures below 316_C
(600_F), the EWT and EUT should be used when Class
V shutoff is required. See table 4 for availability and
temperature limits and figure 2.
TheBoreSealemploysametalCshaped seal ring that
is secured to the outside diameter of the valve plug.
When the valve plug comes into contact with the seat
ringtoclosethevalve,theBoreSealiscompressed
against the cage wall, thereby blocking a secondary
leakage path that exists between the plug and cage
wall. When the valve plug is not in contact with the
seat ring (i.e. valve open), theBoreSealisnotengaged
and the piston rings that are also secured to the
outsidediameteroftheplugassumetheroleof
blocking this secondary leakage path.