Achieving better accuracy in flow control with a unique plug shape
Mr. Da Shi
Technical Product Manager for Metso Flow Control, Shanghai
In this week’s post, our colleague Steve Da Shi is explaining the features and how does the Finetrol balanced plug control performance differ from the other eccentric plug designs:
Although Finetrol belongs to the eccentric plug valve category (IEC 60534-1 Sect 188.8.131.52), it has design differences that distinguish it from other eccentric plug valves currently available on the market. One of the special design features is a balanced plug that delivers benefits when it comes to better accuracy in flow control.
The patented Finetrol™ plug is contoured with a plug tail-element that balances the flow force and provides a wider valve opening from 0° up to 90°. The normal eccentric rotary plug valve only opens up to around 60°.
In a conventional eccentric plug design, the flexible arm connection between the plug and valve stem generates additional torque against the valve stem by the flow forces. Depending on the available actuator torque, this can create challenges for the valve’s controllability and stability, especially when the valve opening is small. Please see the video of Finetrol™ operating movement below:
To improve controllability and stability, Finetrol’s plug balances the flow forces by bringing them closer to the stem’s centerline to reduce the dynamic forces during valve operation. Thanks to its unique plug shape, the tail element of the Finetrol plug can be extended to the maximum opening angle – from 50° or 60° to a full 90°.
Cv-value vs opening angle of Finetrol™ and Competitor’s product (size 1½”)
Even if the flow coefficient Cv does not increase by much, Finetrol™ can still modulate the same flow capacity with a significantly wider valve opening range. This results in a much better control resolution, which brings more control accuracy to both large and small flows. Ultimately, this leads to better valve operation, longer lifetime and less maintenance along with a lower risk of compromising production safety.