Variable Resistance Trim (VRT) Anti Cavitation Solutions

High Capacity Anti-Cavitation Solutions

The Dresser Masoneilan Variable Resistance Trim (VRT®) provides a unique solution for cavitation protection in high pressure liquid letdown applications. The VRT offers a custom balance between cavitation protection and valve capacity in a proven design concept with more than 30 years of field experience. The VRT solution is available within the Dresser Masoneilan 79000 and 41005 series control valve platforms.

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Selection Criteria

The Variable Resistance Trim (VRT) solution is an excellent option for applications requiring custom flow characteristics and custom capacity requirements, combined with severe cavitating conditions due to high pressure drops. The VRT is also a good solution where dynamic valve stability and actuator stiffness are key limitations.

Key Features

The Variable Resistance Technology (VRT) features a multi-stage trim design for eliminating cavitation. Multiple stages are generated by passing the process fluid through a series of axially stacked plates that have drilled holes sized and positioned to provide the required level of cavitation protection and flow capacity. The VRT is available in standard design configurations as well as engineered or customized designs for more optimized performance.

Benefits

The alternating plate segments in the Variable Resistance Trim (VRT) provides smooth throttling control. Unlike other stacked plate designs, the segmented plates in the VRT trim provide seamless continuity in flow control avoiding potential "dead areas". The increasing flow area yields high capacity and provides precise control when operating near the seated position. Special designs can be engineered to provide cavitation protection under low-flow conditions while also providing high capacity at higher lifts when cavitation protection is no longer required.