A stainless steel pressure reducing valve is a crucial device for any application that demands maximum hygiene, high corrosion resistance, or specific chemical compatibility.

It is the de facto standard in sectors such as the pharmaceutical, chemical, food, and biotechnology industries.

However, not all stainless steel valves are created equal.

The challenge lies in choosing the correct model among different internal operating technologies: is a piston-balanced, bellows, or diaphragm valve better?

In this guide, we analyze Valfonta’s PRV series, our complete range manufactured in AISI 316L Stainless Steel, to help you identify the exact solution (PRV20, PRV30, PRV44, or PRV45) that your process needs.

Why choose an AISI 316L stainless steel pressure reducing valve?

Table of contents

  • High corrosion resistance: Unlike other materials, 316L offers excellent durability against a wide range of aggressive fluids, demineralized water, pure gases, or steam.

  • Sanitary compatibility: It is the preferred material for hygienic applications. It is essential in laboratories, pharmaceutical plants, and the food industry, as it does not contaminate the fluid. It is complemented by special gasket options (such as EPDM or Viton) or Clamp-type connections.

  • Durability in harsh environments: The stainless steel body does not require painting and perfectly resists chemical cleaning (CIP/SIP) or aggressive environments (marine, chemical plants) without degrading.

Silver reducing valve

*This stainless steel base allows us to build reliable valves for any environment.

The PRV series: 4 models, 3 balancing technologies

Although the entire PRV series is made of 316L stainless steel, its internal technology defines its ideal application. At Valfonta, we use three different balancing principles to cover all needs.

PRV20 and PRV30 models: the reliability of piston balancing

These models are direct-acting valves balanced by a piston. Inside, a piston moves to compensate for inlet pressure oscillations, ensuring that the outlet pressure remains constant. They are the most robust and reliable solution for most gases (such as compressed air or nitrogen) and liquids.

  • The PRV20 model: It is the compact solution in the range, with sizes from 1/4″ to 3/4″. It is perfect for installations in laboratories, machinery (OEM), or end-use points that require a reliable stainless steel valve with reduced dimensions.

  • The PRV30 model: It is the “big brother” of the PRV20, with sizes of 1/2″ and 1″. It shares the same piston principle but is designed as an all-around valve for sanitary plants, laboratories, and industrial process lines.

PRV44 Model: robustness for steam with bellows balancing

The PRV44 model uses a superior technology for high-temperature applications: bellows balancing. Instead of elastomer gaskets (such as NBR or Viton), the PRV44 seals the shaft with an AISI 316L stainless steel bellows. This metal bellows completely isolates the fluid from the actuator and regulating spring.

This feature makes it the ideal valve for steam (its main application), as well as for other fluids at high temperatures, supporting ranges up to 210 °C.

PRV45 Model: high sensitivity for gases at low pressure

The PRV45 model is a highly specialized valve. Although internally it is balanced by a piston, its unique feature is a large diaphragm actuator.

This large diaphragm (with diameters that vary according to the pressure range) gives it extreme sensitivity. It has been specially designed for gases that require a very low outlet pressure. It is capable of precisely regulating pressures as low as 0.01 bar (10 mbar), making it perfect for nitrogen inerting, blanketing of tanks, or high-precision laboratory applications.

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Comparison table: PRV20 vs. PRV30 vs. PRV44 vs. PRV45

To help visualize the complete range and facilitate a quick pre-selection, we have summarized the key specifications of the stainless steel PRV series in the following table:

Features PRV20 (Compact) PRV30 (Standard) PRV44 (Steam) PRV45 (Sensitive)
Body Material SS 316L SS 316L SS 316L SS 316L
Mechanism Piston Balanced Piston Balanced Bellows Balanced Piston Balanced (Diaphragm Actuator)
Main Fluid Gases and Liquids Gases and Liquids Steam, Gases, Liquids Gases (low P), Steam, Liquids
Max. Temp. 80°C 150°C (with Viton) 210°C 180°C (steam)
Outlet P. Range 0.2 – 20 barg 0.5 – 12 barg19 0.5 – 12 barg20 0.01 – 8 barg
Sizes (DN) 1/4″ – 3/4″ 1/2″ – 1″ 1/2″ – 1″ 1/2″ – 1″

Some of our most requested valves:

Installation flexibility: a key advantage of the PRV series

One of the great advantages of the entire PRV range (PRV20, PRV30, PRV44, and PRV45) is that its internal design allows them to be installed in any position. This offers enormous flexibility to the engineer or installer, who does not always have an optimal horizontal pipe section available.

Although they are very versatile, there are recommended positions to ensure the best performance:

  • Standard position: It is recommended to install them in a horizontal pipe, with the actuator (spring) in a vertical position pointing upwards.

  • Permitted position: It is also possible to mount them on a horizontal pipe with the actuator pointing downwards.

  • Not recommended position: Although mechanically possible, it is not recommended to install them with the actuator “lying down” (in a horizontal position), as the valve may not work as precisely.

Regardless of the position, there are two golden rules that apply to all installations:

  • Cleaning and filter installation: Before installing the valve, the pipe must be cleaned of impurities. It is highly recommended to install a strainer filter just in front of the valve to protect the closure and seat from erosion or blockage.

  • Start-up: When starting the system, the shut-off valves must be opened slowly to avoid water hammer that could damage the internal components of the valve.

Frequently asked questions about the stainless steel PRV series

Both are excellent, but for different fluids. The piston of the PRV30 is a robust solution ideal for gases and liquids. The bellows of the PRV44 uses a metal seal that makes it the best option for steam and high-temperature applications (up to 210 °C).

The PRV45 model. It has been specifically designed for gases that require a reduced outlet pressure. Its large diaphragm actuator allows it to regulate pressures from 0.01 bar (10 mbar).

This term, used in our manuals, refers to the fact that the valves are self-operated and do not require lubrication, calibration, or constant adjustments. However, like any industrial equipment, the gaskets and parts subject to normal use should be checked periodically and replaced if necessary. Always use original Valfonta spare parts.

Yes. Although the PRV44 is the steam specialist, its design and materials make it perfectly suitable for liquids and gases of group 2.

The complete Valfonta catalog for your installation

This range of stainless steel pressure reducing valves from the PRV series is just one part of the comprehensive solution that Valfonta offers for fluid control. Depending on your application, we also manufacture other series of reducing valves (such as the M1 and M2), pressure relief valves, control valves, ejectors, and injectors.

Contact our technical team for expert advice. We will analyze your fluid, pressure, temperature, and flow rate to select the exact PRV model that your process needs.

You can fill out our contact form or call us directly at 93 37 208 88.

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