Pressure Excess Valves type S3 | Valfonta

Valfonta S3 – Pressure Relief / Inlet Pressure Retention Valve

The Valfonta S3 is a self-acting spring-loaded pressure relief valve designed to maintain upstream pressure at a specified set point. When the inlet pressure exceeds the set point, the valve opens proportionally, discharging flow to the downstream line or bypass. Note: This is not a safety valve; separate safety devices are required for equipment overpressure protection.

Technical Specifications

• DN15–DN100, with DN125–DN150 upon review
• Flanged connection EN or ANSI
• BSP, NPT, BW, or SW connections on request
• PN25 for GGG40.3 / RG10, PN40 for 1.0619 and CF3M
• Body materials: GJS-400-18-LT, RG10 bronze, GP240GHN / 1.0619, CF3M / 1.4404
• Trim: stainless steel AISI 316L
• Pressure setting: 0.5–20 barg, with various springs
• Kvs: 3.5–130 m³/h in dimension table; product page states up to 115 m³/h, verification required during sizing.

Temperature and Sealing

The S3 is suitable for steam, Group 1/2 gases, and liquids. For materials 0.7043 and 1.0619, the technical sheet specifies -10 to 250°C, while for stainless steel 1.4408 / CF3M, it specifies -30 to 250°C. Sealing options include metal-to-metal Class IV or PTFE+graphite Class VI. PEEK, NBR, EPDM, stellited seat, and special gaskets are also available.

Installation and Selection

Selection is based on flow rate, set pressure, allowable overpressure, Kvs, temperature, body material, and sealing type. The valve should be installed with the flow direction of the body, upstream filter, and control gauge. For heavy sizes, suspension is from the body, not from the adjustment screw or control lines.

Typical Applications

• Pump bypass in water or thermal oil networks
• Pressure retention in steam collectors
• Overpressure relief in process gas lines
• Industrial liquid lines with stable upstream pressure

Standards

Documentation references PED 2014/68/EU, ISO 9001 quality system, and ATEX 2014/34/EU with a technical dossier for relevant versions.