Solving the problem of cavitation and plugged needle valves

10 December 2013

Problems relating to cavitation and plugged needle valves can be challenging for plant engineers. The AS-Schneider S371 series is said to offer a solution. 

The Y-Pattern Needle Valves Type S371 from Armaturenfabrik Franz Schneider GmbH + Co can be used as shut-off valves in impulse lines, where a low-resistance passage and less deflection of the flow are important, or where the valve must be easily rodded. 

A flow generally does not occur in impulse lines – except when blowing off or flushing the lines. However, while blowing off steam lines, the small flow cross sections and high pressures can result in high flow velocities, which, when combined with deflection of flow, can lead to cavitation which can damage the valve tip and the valve seat.

The AS-Schneider S371 series was developed specifically for this application and, unlike other needle valves, features a truly straight-through design without any deflection of flow. Ball valves also have these good flow characteristics, but here a metal sealed design must be used for high fluid temperatures, which is costly. The S371 Series, therefore, can be a good compromise between the requirements of flow characteristics and valve technology. 

Another advantage of the valve is the space-saving arrangement of the valve head unit relative to the impulse line. 


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