Flanged Type Double Offset Butterfly Valve

Advantages of double offset valves:

split stem allows higher values；

lower pressure loss；

sealing ring and seat come to contact only nearly after the valve is entirely shut；

low closing tor ue；

the seal guarantees perfect upper stem tightness；

water and air tightness；

actuator connection can be done by bracket or the stem can be extended if connected o special actuator types.

Design Advantages:

Double offset

the double offset design provides a safe function and tightness even after a sudden temperature or pressure change. It reduces seat wear and ensures perfect tightness. The first offset (1) shifts the axis of the rotation off the sealing surface and thus provides tightness between the seat and the sealing ring around the entire disc circumference. The second offset (2) shifts the stem off the pipeline axis; the sealing ring leaves the seat after a few degrees of opening movement. The reason of the second offset is to quickly relieve the seal from compression between the disc and the seat. Rotating movement is changed to the linear one and the disc is effectively pressed into the seal. The design also prevents undesirable agglomerating e. g. undissolved substances in the area of disc and seal contact.

(1) - stem axis is off the sealing surface

(2) - stem offset off the pipeline axis

Stem and seal

to the split stem the valve attains higher values of Kv/Cv and related low-pressure loss

adjusting seal according to the customers' requirements - the seal can be tightened to the parameters prescribed by customers. Thus maximum tightness can be achieved around the stem

actuation torque for low-pressure applications can be decreased

adjustable seal without dismantling the actuator

stem assembly - upper and lower bushings made from TP Igus provides high abrasion resistance and prolongs valve lifespan

CF8

extended neck - enables to insulate piping incl. the valve

easy service and seal replacement

easy assembly and replacement

top flange according to ISO 5211 enables to directly install a manual handle or an actuator

Seal design

CTFE suitable seal geometry ensures full tightness and a high number of cycles. The PTFE seal is reinforced with 25% carbon fibres, reducing wear and increasing valve thermal stability. Longer lifespan of the valve and lower maintenance demand are guaranteed.

end-stops - are designed to avoid the disc overruning the maximum allowable position. Thus the seal is not damaged nor overloaded and the valve lifespan is extended

Material Performance:

Operating Torques / Flange Connection

Operating torques (Nm) vs. working pressure (bar) R-PTFE seat (standard line DN50-DN300)

1.Operating torques are mentioned without safety reserve

2.This torque is tested in the direction of the valve body arrow, the valve stem is in the upstream direction

Basic Dimensions