Finetrol's plug shape – Ask the flow control expert

A: Finetrol belongs to the eccentric plug valve category (IEC 60534-1 Sect 3.1.2.5), but it has design differences, which distinguish it from other eccentric plug valves on the market. One of these is Finetrol’s balanced plug that delivers benefits in practical control duty.  

The patented plug design provides a wider opening range

The patented Finetrol plug design (see image below) is contoured with a plug tail-element that balances the flow forces and provides a wider opening range from 0 up to 90 degrees. The plug balances the flow forces by bringing the total flow force close to the stem’s center line, which means that the effect of dynamic forces on valve operation and control stability is minimized. This is not the case with a conventional eccentric plug design, where the flexible arm connection between the plug and valve stem acts like a torque arm to allow the flow forces to generate additional torque against the valve stem. Depending on the available 35 actuator output torque, this can create challenges to 30 the valve’s controllability and stability, especially at low valve-opening angles.

More accurate control of smaller flow-rate changes

Another practical benefit of the Finetrol plug shape is its full 90-degree opening range. The tail-element of the Finetrol plug extends the maximum opening angle of traditional eccentric rotary plug valves from 50 or 60 degrees up to 90 degrees (Figure 2) This means that with Finetrol the equivalent flow capacity is presented to a wider opening range. As a result, smaller flow changes can be controlled using Finetrol Competitor the same degree of opening change, giving more accurate control of smaller flow-rate changes with the Finetrol control valve.  

The Finetrol plug