The PRV55 pressure relief valve from Valfonta is a high-precision self-regulating device designed to keep the main line pressure constant, relieving the excess flow when the setpoint is exceeded. Unlike other models, this device combines a membrane actuator with a stainless steel bellows, allowing it to work with very low setting pressures (from 0.01 barg) with high sensitivity.
Manufactured entirely in AISI 316L Stainless Steel (body, internals, cap, and bellows), it is the ideal solution for applications in the chemical, pharmaceutical, and food industries that require cleanliness, corrosion resistance, and zero emissions. Its robust yet sensitive design makes it suitable for steam, gases, liquids, and compressed air, ensuring tight shut-off and immediate response.
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Dimensional Range: Sizes 1/2" (DN15), 3/4" (DN20) and 1" (DN25).
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Maximum Inlet Pressure: Up to 25 barg.
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Regulation Ranges (Low Pressure): Thanks to its membrane, it offers very fine adjustment ranges:
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0.01 to 8 barg (specific springs available for ranges 0.5-4 / 3-8 / 4-12 bar upon request ).
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Differential Element:
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Membrane: Detects small pressure variations.
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Bellows: Balances internal pressures and ensures shaft tightness.
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Working Temperature: From -30°C to +210°C.
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Materials: "Full Inox" construction in AISI 316L.
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Connections: Threaded BSP / NPT and Flanges DIN / ANSI.
The PRV55 valve operates by direct action:
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Detection: The inlet pressure is transmitted to the actuator chamber (where the membrane is located) through a command line (internal or external).
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Proportional Opening: When the inlet pressure exceeds the force of the regulating spring, the force on the membrane pushes the shaft and opens the valve.
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Balance: The bellows and piston balance the backpressure forces, enabling the valve to modulate smoothly.
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Relief: By releasing the fluid, the pressure in the main line drops. When it falls below the setpoint, the spring closes the valve.
Due to its sensitivity and use in critical applications (such as steam), please follow these instructions:
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Filtration: It is essential to install a strainer filter before the valve to protect the membrane and the seat.
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Mounting Position:
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Liquids and Gases (< 80 °C): It is recommended to install in horizontal piping with the actuator facing upwards.
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Steam (> 150 °C): Must be installed on horizontal piping with the actuator pointing downwards to protect the membrane from the direct temperature of the steam.
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Control Take-off:
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Gases: Usually uses the internal take-off.
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Liquids > 125 °C and Steam: Requires external control take-off connected to the main pipe 1 meter from the valve.
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Condensation Tank: Mandatory for steam and high temperature liquids (>125°C). It must be installed at the highest point of the command line and filled with water before start-up.
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Adjustment: To increase the relief pressure (compress spring), turn the screw counterclockwise. To reduce it, turn it clockwise.
