Ratio Pressure Reducing Valves

In complex water distribution networks with significant elevation changes, maintaining acceptable pressure at all points often requires pressure management at multiple locations. Standard pressure reducing valves maintain a fixed downstream setpoint regardless of upstream variation. In some applications, particularly where a fixed proportional relationship between upstream and downstream pressure is more appropriate than a fixed setpoint, a ratio pressure reducing valve provides a more precise and stable control function.

A ratio PRV reduces downstream pressure to a fixed percentage of upstream pressure. If the upstream pressure is 10 bar and the ratio is set to 0.5, the downstream pressure will be 5 bar regardless of demand fluctuations or upstream pressure variation. As upstream pressure rises or falls, the downstream pressure tracks it at the same ratio. This behaviour is particularly valuable on trunk mains where upstream pressure varies significantly with reservoir level or pump operating point and where a fixed downstream setpoint would result in excessive pressure variation at distribution level.

The ACV ratio reducing valve from AFC Valves Europe is a hydraulically operated diaphragm valve with a ratio pilot valve that senses both upstream and downstream pressure and modulates the main valve to maintain the set ratio. No external power is required. The valve is constructed to the same standards as the rest of the automatic control valve range: ductile iron body, stainless trim, EPDM diaphragm and flanged connections to EN 1092-1.

Ratio PRVs are also used in tandem with standard pressure reducing valves as part of pressure management schemes for district metering areas (DMAs). In a cascaded arrangement, a ratio valve on the trunk main outlet reduces the incoming pressure to a stable intermediate level and a downstream PRV then reduces this to the final distribution setpoint. This two-stage arrangement improves setpoint stability and reduces valve hunting in networks with highly variable demand profiles.

Applications include trunk main pressure management in hilly terrain, direct supply connections from high-pressure transmission mains to lower-pressure distribution zones and booster station outlet pressure management where the booster inlet pressure varies with raw water source level.

AFC Valves Europe supplies ratio pressure reducing valves in DN50 to DN400 with PN10 and PN16 flange connections. Our technical team can advise on ratio setting, pilot selection and installation requirements for specific network conditions. Full documentation including pilot circuit diagrams and commissioning records is supplied with every valve.