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What is the front seal and back seal for the ball valve?

April 23, 2017

In addition cinder ball valve, spray ball valve pulverized coal, others, like the floating ball valve, trunnion mounted ball valve, V-type ball valve, eccentric semi-ball valve, three way ball valve, which has two seats, the first seal means that the inlet end seat acts as a seal, the back seal means that seal the outlet end of the seat from the actual principle is very simple, which is to seat sealing O-ring sealing surface on the outside of the seat within the differences and. There is also a two-way sealed DIB structure; its principle is to increase the O-ring, the inner circle within the valve seat ring, the outer ring outside the seat.

 

After the back seat seal trunnion ball valve, the fluid pressure on the ball and seat effective force is small, therefore, the bearing load and friction torque are small, which gives the drive and bearing design, especially for low friction coefficient with self-lubricating properties, but the choice of compressive strength is low, there is a tendency of cold PTFE sliding bearings to provide a convenient, the disadvantage is that the valve seat seal: To ensure da> dw, if not reduce the valve channel cross-sectional area, it is necessary to increase the size of the ball and the body’s structure.

 

For the first seal, the back sealed on both sides of trunnion mounted ball valve, the advantage of reliable sealing performance, low bearing loads, so it is suitable for sealing particularly demanding situations, when the ball valve body cavity pressure P2 abnormally elevated, it cannot automatic pressure relief, therefore, when using double sealed ball transporting liquefied gas, the need to coat the body of a small safety valve.

 

When the fluid pressure PN≥16MPa, valve size DN = 80-200mm, the general use of the back seat seal, for delivery pressure PN≤10MPa corrosive media and gases, as well as valve size larger occasions, should be adopted valve seat before sealing, the sealing requirements are particularly stringent, or more dangerous media, we recommend using double-sided seal valve, in order to increase the sealing performance, reduce friction and wear seat, extend its life and to prevent the ball valve use due to damage caused by accident seat, oil seal structure can be added in the seat, but it must be noted that only the auxiliary oil seal from the seal, or as a temporary emergency measure, oil seal structure used for larger diameter and conveying gas trunnion mounted ball valve medium.

 

Should you want to know more about ball valve from Reliable China valve manufacturer, please visit www.reliavalve.com or email us via sales@reliavalve.com.

 

Contact Us

 

Zhejiang Relia Valve Co., Ltd.

Sanqiao Ind. Zone, Oubei Town

Wenzhou, Zhejiang, 325105

P.R.China

 

Tel: + 86-577-86373155

Fax: + 86-577-56994545

sales@reliavalve.com

Website: www.reliavalve.com

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