double eccentric geometry of the disc rotating center
seat is designed as a tilted cone geometry
seat is floating inside the disc profile, seat will
be shaped into an elliptical form at closed position
continuous line contact between seat and seal of
body and disc. the dimensions change duo to temperature
influences leads the seat ring to alternate seating
position during the cone geometry.
seat rings both of body and disc are solid and real
metal, can't be flushed away as lamellar seat.
The value getting from Fig. 2specifies the Actuator
Torque required for closing the valve . Since the
valve being a torque seatrd design , the closed
position of the valve is mot self-locking,the actuator
has to keep the torque valve during the valveat
The values show in Fig.2 are valid for metal seated
valve with a seal qualified to IEC 534-4 class IV.
For higer tightness requirement i.e. IEC534-4 Class
IVS and V, the torque value has to be multiplied
value getting from Fig. 3 specifies the Dynamic Torque
of the valve during open position.The values are valid
for Bi-directional flow and expressed in torque per
p-unit i.e. in Nm/bar or in ft-bl/psi.
In general, the dynamic torque of seated butterfly
valve is smaller then the closing torqud shown in
Fig.3. Only relative large valve size working under
a high pressure drop can have dynamic torque valre
of significant. It must ne considered that the vslue
of the pressure drop shall never ve higher than the
product out of XTxP1
resp. FL2 x (P1-Pv).
Where XT : Pressure
differential ratio factor
P1 : Inlet pressure.
Pv : Saturated vapor pressure of the liquid at the
inlet temperture (kgf/cm2abs)
FL: Liquid pressure recovery factor