The S2 pressure relief valve from Valfonta is a self-actuated device designed to control and limit the inlet pressure in a process line. Its main function is to maintain the upstream pressure at a constant value: when the pressure exceeds the set point, the valve opens proportionally to release the excess fluid to a return or recycle line.
It is a versatile and efficient solution for working with steam, compressed air, gases, and liquids. Unlike traditional safety valves (which open suddenly), the S2 offers stable, modulating regulation. Its design incorporates a compensation system and a reinforced membrane with intermediate fabric, ensuring a fast, precise and long-lasting response to system pressure changes.
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Dimensional Range: Available from DN15 up to DN100.
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Maximum Inlet Pressure: Up to 10 barg (versions up to 16 barg available on request).
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Regulation Range: Allows setting relief pressure between 0.02 and 10 barg by different actuators and springs.
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Body Materials:
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Ductile Iron (GGG40.3) for PN25.
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Carbon Steel (WCB) and Stainless Steel (CF3M) for PN40.
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Internal Parts: Seat, plug, and internal parts made from AISI 316L Stainless Steel.
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Temperature Limits:
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NBR: -20°C to 80°C.
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EPDM: -40°C to 125°C.
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PTFE (with condensation tank): 40°C to 180°C.
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Connections: DIN Flanges (PN16-PN40), ANSI (150/300 lbs) and BSP / NPT threads (up to 2").
The valve operates on the principle of direct action through the balance of forces on a diaphragm:
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Sensing: The inlet pressure (upstream) is transmitted to the actuator chamber, usually through an internal connection (external upon request).
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Opening: This pressure exerts a force on the diaphragm and closing assembly. When this force exceeds the spring tension set by the user, the valve begins to open.
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Modulating: The valve opens proportionally to the pressure increase. The greater the excess pressure, the more the valve opens to evacuate the fluid.
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Closing: As soon as the inlet pressure drops below the set value, the spring pushes the closing assembly down, sealing the valve again.
To ensure correct operation and safety of the equipment:
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Mounting Position: It must be installed in a horizontal pipe, following the flow direction indicated by the arrow.
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Standard: Actuator vertically upwards (Required for any fluid at T > 0°C).
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Inverted: Not recommended, as the valve might not behave properly.
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Control Connection:
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Standard: Supplied with internal pressure connection, so no installation of external piping is required.
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For Steam: External connection required. It must be connected to the main pipe (inlet) at a distance of at least 1 meter from the valve.
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Condensation Tank (Drum):
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Mandatory for steam applications or liquids at T > 125°C.
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Its function is to protect the membrane from overheating. It must be filled with water to overflow before start-up.
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Filtration: It is highly recommended to install a strainer filter at the inlet to avoid damage to the closing assembly and reduce maintenance.
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Adjustment: Turn the top screw clockwise to increase relief pressure and counterclockwise to decrease it.
