Seal pneumatic valve structure and working principle

Lever hoist structure
Lever hoist structure . When the valve is closed, the spindle and the lever with the taper pin fastened around the point o counterclockwise rotation , lever driven off with perforated disc ab, by a compression spring to promote the disc fixed fulcrum on n , with the spindle lever rotates. When the butterfly plate upper b and valve sealing surface to seal all contact . Open the process is reversed . In the opening and closing process , the relative sliding sealing small , reducing the relative wear . In the off state for the axial pressure seal , to change the traditional external compression seal.
By force type actuator rod
By force type actuator rod , the piston in the air under pressure to the right, sliding rod drive arm in the housing , the connecting rod affects rocker clockwise , the output torque. The rod and rocker length (h) the same is equal to the output housing groove cardiac center . Case groove walls subjected to lateral thrust f, p affects rocker rotating component , according to the force analysis shows that:
p = q / cosαα = sin-1 (1-sinβ)
m Twist = phcos (90-α-β) = qhsin (α + β) / cos (α + β)
From the above equation , β angle decreases , α angle increases , m torque value increases. When β = 0 °, α = 90 ° (the valve is closed) , the maximum output torque of drive means ,marker cable ties and in the opening and closing process of the torque is small. This feature is exactly on the curve inclusive of valve operating torque curve , to meet the butterfly valve in the closed or open state seal required torque .
Flat sealing structure
Past pneumatic valve seal pair commonly used spherical sealing , the sealing pressure is radial compression force , the sealing amount of interference can not be adjusted , depending on the sealing performance of the sealing material amount of interference , therefore, the design of the sealing material selected the amount of interference is very important . At work, in particular in zeolite pre-purification process, the switching valve is operated in the range of 10 ~ 200 ℃ , when using the rubber seals , rubber, linear expansion coefficient is large , by the temperature change is large , the amount of interference is difficult to accurately OK. If interference capacity, not only increase the friction , and often appear to "bite edge" and "turn tongue" phenomenon, so seal failure , a small amount of interference appeared leak. Even if the amount of interference reasonable choice , and this valve switching frequently over time due to wear and after the operation will fail . If the use of non-rubber sealing materials, according to information known at present , their elastic deformation is small, the radial seal interference is difficult to control, manufacturing complexity , high cost. While the rubber seal materials, changing the temperature , the temperature of the rubber seal and cause premature aging of the fatigue damage , for large air separation unit is equipped with large-diameter pneumatic butterfly valve, replace the seals will be very difficult.
Since the movement of the valve plate using leveraged institutions , when the valve plate is closed , the valve plate sealing surface contact with the valve seat to become subsequently lever cam mechanism equivalent , if the spindle continues to rotate , then translate the valve plate forward to continue to achieve the balance of forces with working medium pressure, but also to achieve self-sealing , ensure the sealing reliability. When the wear of the sealing surface , the seal also has an automatic wear compensation characteristics , thereby extending the service life.
New sealing pneumatic valve is used flat metal seal structure , the valve as a non- consumable welding of stainless steel alloy, copper alloy seat seal ring with cobalt alloy or stainless steel welding generations , nylon zip ties they are highly resistant to corrosion and abrasion resistance , temperature range, between -40 ~ 300 ℃ in long-term use , so much more life than rubber seal .