Flowserve Butterfly Valve - Manual (Page 5)

5
SECTION II
BUTTERFLY VALVES
FOR USE WITH MANUAL GEAR ACTUATORS
The Flowserve 150 Class Butterfly Valve contains improvements and refinements not found in any
other extended performance Butterfly Valve. These features serve to ensure a long and trouble
free life as well as making maintenance much simpler and less expensive when it is finally
required. This section of the manual is divided into seven (7) sections: (1) Design Features, (2)
Installation, (3) Operation, (4) Disassembly Instructions, (5) Assembly Instructions, (6)
Maintenance Instructions and (7) Long Term Storage. (NOTE: The piece numbers referred to in
this section are detailed on drawing.
Operation and Maintenance Instructions for the Manual Gear Actuator is located in Section IV
1.0
DESIGN FEATURES
1.1 Seat Design
The Flowserve Butterfly Valve employs a pressure energized spring seat design
which seals proportionally tighter as the pressure increases. In addition the spring
seat design is self-compensating for any slight misalignment which may occur.
When the valve is closed the disc is squeezed into the seat for initial sealing. There
upon upstream pressure amplifies the seat bearing pressure against the disc to
further effect a tighter seal. The higher the pressure the tighter the seal.
1.2 Body Design
Flowserve Butterfly Valve employs a rugged one-piece body design with installation
bolt holes for flange bolts. These bolt holes (if provided) have sufficient clearance to
allow flexibility for misalignment of mating flanges.
1.3 Gland Design
Flowserve Gland Packing is a preformed Grafoil Design. These packings offer
excellent sealing characteristics along with minimum torque build-up. Adjustment,
when necessary, can be accomplished by tightening the gland retainer nuts with
simple hand tools.
1.4 Disc Design
The Flowserve Butterfly Disc is of rugged construction with a sealing edge which is a
segment of a ball. Once the disc is squeezed into the seat, a leak tight seal is
affected. Any minor change of position of the disc, once it is squeezed into the seat,
will not affect performance. The result being that (within the width of the edge) an
exact stop position is not critical. In addition, if the edge of the disc should become
damaged it may be possible to reposition away from the damage area, thus avoiding
a valve overhaul or replacement.