BUTTERFLY VALVE

[dbz]

Whats the advantage of 2nd offset in double offset butterfly valve??
i read in many forums and catalogue that its helps in reducing the torque and allows quick opening.can some one explain it in detail ?
any help will be appreciated.

 

[btrueblood]

The valve "lifts" off the seat, rather than sliding across it.

 

[gerhardl]

Additional to btrueblood:

The advantages have been discussed several times, and I suggest you use the forums' search motor to expand.

Briefly a high quality double eccentric BFL valve will have a far longer standtime before seat sealing change than a normal/'single' eccentric valve of high quality. Advantage increasing with higher pressure, higher diameter, more difficult access. Less sticking and wear to seat sealing, easier seat exhange.

The opinions differ about how large the advantages are.

 

[al1979]

"The valve "lifts" off the seat, rather than sliding across it"

In other words disc get disengaged quickly from seat along the shaft. 2nd offset helps only & only for this quick disengagement. It should be kept enough to achieve quick disengagemnet without increasing unbalanced / offset torque.

 

[dbz]

thank you btrueblood,al1979 !
gerhardl thankyou for ur explanation.as u said i went through many forums but was not able to find it.
can u provide me links of the forums it will be really helpfull.