Pressure Excess Valves type S1 | Valfonta

Valfonta S1 – Inlet Pressure Retaining Valve

The Valfonta S1 is a self-actuated globe-type overpressure valve with a single seat, designed for proportional opening when upstream pressure exceeds the set point. Pressure is transmitted to the actuator via an external control line, and adjustment is mechanically achieved through the spring, requiring no auxiliary energy.

Technical Specifications

• DN15–DN150, with Kv 3.5–240 m³/h
• PN25–PN40 / Class 150–300
• Maximum inlet pressure: 15 barg
• Adjustment range: 0.5–15 barg
• Connections: EN / ANSI flanges, BSP or NPT threads upon verification
• Body materials: GGG40.3, ASTM A216 WCB, ASTM A351 CF3M
• Trim: Stainless steel AISI 316L
• Diaphragm: NBR -20 to 80°C, EPDM -40 to 125°C, EPDM+PTFE 125 to 220°C

Media and Applications

Suitable for steam, compressed air, neutral gases, and liquids. Used in pump bypasses, steam networks, return lines, exchangers, process collectors, and locations requiring upstream minimum pressure maintenance. Does not replace a safety valve; separate safety arrangements are required for overpressure protection.

Installation

The S1 is installed in horizontal piping, with flow direction as indicated on the body. Clean piping and a filter are required upstream of the valve. The control line connects to the upstream piping, at least 1 m or 10×DN before the valve. For steam or liquids above 125°C, a condensate pot is necessary for diaphragm thermal protection.

FAQ

How is the size selected?
Based on flow rate, allowable pressure drop, set point, Kv, temperature, and body material.

What is needed for stable regulation?
Proper pressure tapping, upstream filter, gauges before/after, and avoidance of mechanical loads from piping.