The Design Principle of Segment Disc Control Valves

Figure 1.

The central throttle device of this control valve is two discs with segmented openings which slide on one another and seal against each other (Fig. 1). The segment discs are positioned vertically in the valve housing, facing the direction of flow. A moving disc is placed upon a rotationally fixed segment disc, the geometry of which determines the throughput capacity and characteristic curve. These two discs have the same number of segments and the moving disc is rotated via a push rod which is tangentially inserted. Consequently, the cross-section surface of the free segment passage changes when a control intervention is made.

Irrespective of the pending pressure differential, the moving segment disc is pressed onto the fixed disc via a spring pack- age. This ensures that the direction of flow is variable and that the valve can be installed in any desired location. Due to the fact that there are no metal seats with ring-shaped contact surfaces, no grooves will occur which can rapidly lead to leaks in traditional steam valves. Leakage ratios amounting to < 0.001% of the K_vs value are constantly achieved with the significantly less vulnerable surface seal.

Extremely robust segment disc valve from
Schubert & Salzer for steam distribution.

Thanks to this special design, segment disc valves are one of the few valves that are able to combine control precision and a high level of tightness, even in extreme conditions and which also experience hardly any wear.

The standard segment disc valves are available in finely graduated intervals of between DN 25 and DN 300 – and go up to DN 800 where necessary – in an intermediate flange design for nominal pressures up to PN 25. They can be used for media temperatures ranging between -60°C and +220°C (higher temperatures and nominal pressures are available on request). The robust valves have a rangeability of 60:1.

For more information, contact Miller Energy, Inc. by calling 800-631-5454, or visit their web site at https://millerenergy.com.