ACTUATION
Rethinking actuation for reliability and TCO
The development and deployment of specialised Ratio Reducing Valves marks a necessary evolution in flow control technology.
By Peter Telle, Ultra Valves
Ultra Ratio Reducing valve
The Pressure Reducing Valve( PRV) is a vital tool for network management, controlling transient pressure and reducing non-revenue water( NRW) loss. However, its traditional reliance on complex external pilot systems introduces vulnerabilities. While standard PRVs maintain a set downstream pressure, extreme highhead systems— common in deep mines or mountainous municipal networks— demand a valve dedicated to safely dissipating vast amounts of pressure before distribution. This is one of the functions of the Ratio Reducing Valve( RRV). The core challenge of this duty is not precise setpoint regulation, but gross pressure dissipation while protecting the valve’ s material integrity against high velocity and cavitation. An RRV is engineered to maintain a fixed reduction ratio between inlet and outlet pressures( e. g., 3:1 or 4:1), making it fundamentally different from a piloted PRV.
Engineering for controlled energy dissipation
The design of a reliable RRV focuses on robust simplicity and staged pressure reduction to manage energy safely. 1. Fixed piston actuation: Unlike standard PRVs that use sensitive, multi-component pilot systems, the RRV relies on a simple, robust piston mechanism. This mechanism mechanically maintains the fixed pressure differential across the valve, regardless of
flow variations. This eliminates the intricate tubing and small orifices that are prone to fouling and calibration drift in conventional systems.
2. Series stability: A key technical advantage is the valve’ s stability when multiple units are installed in series. In applications where upstream pressure is too severe for a single component, two or three RRVs can be installed sequentially to stage the pressure reduction. This capability is essential, as pilot-operated PRVs typically become hydraulically unstable when installed in series, rendering them unsuitable for this type of ultra-highpressure dissipation.
3. Material integrity: Given the extreme service conditions( up to150 bar), internal components, and particularly the trim, are subject to intense erosive forces and the risk of cavitation. RRV internals are therefore manufactured from highly resistant materials like hardened stainless steels or specialised metallic alloys. The emphasis is placed on longevity under sustained, severe pressure drop.
Operational reliability and TCO impact
The RRV’ s simplified and robust engineering yields distinct operational and financial advantages, directly contributing to a lower Total Cost of Ownership( TCO). Key features are: Superior fail-safe capability- This is perhaps the RRV’ s most significant reliability feature. Unlike
30 Valve World December 2025 www. valve-world. net