A pressure reducing valve (PRV) - also known as a water pressure regulator valve - is designed to automatically reduce high inlet pressure to a lower, stable outlet pressure. These pressure control valves are commonly used in water and hydronic heating systems, as well as in industrial pipelines, to protect equipment and maintain safe operating conditions.
Without a pressure-reducing valve, excessive pressure can damage pipes, fittings, pumps, and other system components. Installing the right PRV ensures consistent performance, longer equipment life, and improved system efficiency.
How Does a Pressure Reducing Valve Work?
A water pressure reducing valve works by automatically adjusting its internal components to maintain a constant downstream pressure, regardless of fluctuations in inlet pressure. Most PRVs use a diaphragm or piston to sense pressure changes and adjust the valve position accordingly. When inlet pressure exceeds the valve’s set point, the diaphragm or piston moves, opening the valve and allowing fluid or gas to flow through. As the fluid passes through an internal restriction, the pressure is reduced to the desired level.
A spring mechanism applies force to keep the valve closed when pressure is below the set point. This spring is adjustable, allowing users to set the desired downstream pressure.
There are more sophisticated PRVs, such as pilot-operated valves. In this option, a pilot system monitors pressure and provides feedback to the main valve. This allows for more precise control, especially in systems with higher flow rates or fluctuating pressures.
Key Features of Pressure Reducing Valves
Modern water pressure valves can be used for residential, commercial, and industrial applications and are designed with features that ensure reliability, accuracy, and long-term performance. Below are the key features of the PRVs.
Self-Contained Pressure Control
Pressure-reducing valves are equipped with a diaphragm or piston that senses the upstream pressure of the fluid in the loop. When the upstream pressure exceeds the valve's set point (pre-calculated and set), the diaphragm or piston moves to open the valve and allow fluid or gas flow. As the fluid or gas flows through the valve, it encounters a restriction orifice that reduces the pressure and maintains a constant downstream pressure.
A spring within the valve applies a force to the diaphragm or piston, keeping the valve closed when the upstream pressure is below the set point. The spring is adjustable, allowing the set point to be changed as needed.
In some cases, pressure-reducing valves may also be equipped with hydraulic components, such as a pilot valve or pilot line, that help to control the valve's opening and closing. The pilot valve or pilot line is connected to the diaphragm or piston. It uses a pressure signal to modulate the valve's position, allowing for precise downstream pressure control.
Precise Control of Downstream Pressure
By combining sensing, regulation, and feedback mechanisms, PRVs precisely control downstream pressure. The valve senses the upstream pressure of the fluid or gas. When the upstream pressure exceeds the valve's set point, the valve opens to allow fluid or gas to flow, reducing the pressure to the desired level.
Water Hammer Protection
A pressure regulating valve can eliminate water hammer under defined conditions by combining design features and operational controls. Water hammer is a hydraulic shock that can occur when a fluid is rapidly forced to stop or change direction, resulting in a sudden increase in pressure that can cause damage to pipes and equipment.
To eliminate water hammer, pressure control valves that act as water pressure regulators may incorporate features such as slow-closing or quick-opening mechanisms, which can reduce the sudden pressure changes that can cause water hammer.
These controls can be particularly effective when the pipeline fluid flow rate undergoes sudden changes, such as during the start-up or shut-down of pumps or other equipment.
Rapid Action
A pressure-reducing valve provides rapid action by immediately sensing and adjusting downstream pressure through its internal sensing, regulating, and feedback mechanisms. This allows the valve to respond quickly and effectively to pressure and flow rate changes, helping maintain a stable and safe operating environment for the pipeline and its associated equipment.
Video credit: Watts
Types of Pressure Reducing Valves
There are several types of pressure-reducing valves, each designed for specific applications and operating conditions. Choosing the right PRV type depends on flow rate, pressure range, and system requirements. The most common types include:
Direct-Acting Pressure Reducing Valves
These valves use a diaphragm or other sensing element to directly regulate the main valve's position and control downstream pressure. They are simple in design and suitable for low-flow applications.
Pilot-Operated Pressure Reducing Valves
This type of valve uses a pilot valve or pilot line to sense the downstream pressure and provide feedback to the main valve. As a result, they can regulate higher flow rates and pressures than direct-acting valves.
Proportional Pressure Reducing Valves
Proportional pressure regulating valves use electronic or hydraulic controls to provide precise, proportional downstream pressure control. They are often used in industrial and process applications where precise pressure control is critical.
Differential Pressure Reducing Valves
These pressure control valves regulate the pressure differential between two points in a pipeline rather than maintaining a constant downstream pressure. As a result, they are often used in applications such as heat exchangers, where a precise temperature differential is required.
Back-Pressure Regulators
This type of valve maintains a constant upstream pressure rather than downstream pressure and is typically used in applications such as fuel systems and chemical processing, where maintaining a constant upstream pressure is critical.
Pressure Reducing Valve vs Pressure Relief Valve
A pressure-reducing valve and a pressure relief valve are similar types of valves used in piping systems to regulate pressure, but they serve different purposes.
What Is The Difference Between a Pressure-Reducing Valve and a Pressure Relief Valve?
A water pressure reducing valve (PRV) is designed to regulate and lower the pressure of a fluid flowing through a pipeline to a predetermined level. This is typically done to prevent excessive pressure from damaging downstream equipment or processes. As a result, a PRV maintains a constant downstream pressure, even when the inlet pressure fluctuates. PRVs are commonly used in steam and gas pipelines, water distribution systems, and industrial processes where precise pressure control is necessary.
On the other hand, a pressure relief valve (also referred to as a PRV) is designed to protect equipment and piping systems from overpressure conditions by releasing excess pressure into the atmosphere or a low-pressure system. The valve is set to open at a predetermined pressure level and relieve the excess pressure until the system pressure returns to a safe level. These PRVs are commonly used in applications such as pressure vessels, pipelines, and storage tanks, where overpressure can cause catastrophic equipment failure or environmental damage.
Comparison Table
| Feature | Pressure Reducing Valve | Pressure Relief Valve |
|---|---|---|
| Function | Reduces pressure | Releases excess pressure |
| Controls | Downstream pressure | Maximum system pressure |
| Use Case | Water, steam, HVAC systems | Safety protection |
| Operation | Continuous regulation | Emergency discharge |
Pressure Reducing Valve Applications
Pressure reducing valves are used anywhere consistent pressure is required. Some of the most common applications are:
- Water Distribution Systems – PRVs reduce high incoming water pressure to safe levels for use in homes, businesses, and other facilities. They can also help prevent damage to water mains and other distribution system components.
- Steam Systems – When used in steam systems, PRVs regulate the pressure and prevent damage to pipes, valves, and other components. They are often used in industrial applications, such as power generation and manufacturing.
- Gas Distribution Systems – Pressure reducing valves regulate pressure and prevent damage to pipelines and other components in natural gas distribution systems. They can also help to improve the efficiency of gas-fired equipment.
- Hydraulic Systems– PRVs regulate pressure and prevent damage to pumps, valves, and other components.
- Process Industries– Pressure regulating valves help maintain precise pressure control and prevent damage to equipment in a wide range of process industries, including chemical processing, oil and gas refining, and food and beverage production.
- Fire Protection Systems– PRVs regulate water pressure and prevent damage to fire hydrants, hoses, and other components, while also helping ensure that firefighters have access to a reliable water source in the event of a fire.
- Homes - Pressure valves can be used in residential applications to ensure the safe and reliable operation of boilers and small water-loop systems.
Overall, water pressure reducing valves are an essential component of many different systems and applications where precise pressure control is critical for safe and efficient operation.
How to Choose the Right Pressure Reducing Valve
When selecting a pressure-reducing valve, consider:
- Pressure Range - Ensure the valve matches the designed inlet and desired outlet pressure.
- Flow Rate- Select the valve based on your system demand.
- Material - Brass for potable water, stainless steel for industrial use, e.g.
- Connection Type and Size - NPT, Sweat, or Flanged, along with their associated connection sizes.
- Application - Water (heating or cooling), steam, or gas.
Not sure which valve you need? Our team can help you select the right PRV for your system.
Benefits of Using a Pressure Reducing Valve
There are several advantages to pressure-reducing valves, including enhanced safety, improved efficiency, longer equipment life, consistent performance, reduced noise and vibration, and improved system stability. Pressure-reducing valves offer a range of benefits that help ensure the safe, efficient, and reliable operation of pipelines, equipment, and systems across various applications.
Summarizing the main benefits of using a PRV are:
- Protects equipment
- Improves system efficiency
- Reduces noise and vibration
- Extends system lifespan
Examples of Pressure Reducing Valves by Manufacturer
At Liberty Supply, we carry industry-leading water pressure valves designed for reliability and performance:
Bell & Gossett Pressure Reducing Valves
Bell & Gossett pressure-reducing valves for home systems set the system pressure to a preset level for optimum performance. Combination dual-unit valves include a pressure-reducing valve and a relief valve.
- Fast fill feature reduces start-up time and labor
- A low-inlet-pressure check valve helps prevent system pressure loss when the supply water drops below the system pressure.
- Convenient, cleanable strainer prevents dirt and sediment from entering the system.
- Union connection available with 1/2" male NPT thread and 1/2" female sweat tailpiece for fast, flexible system connection
- Brass body construction is highly corrosion-resistant and ideal for water systems.
- Lead-free brass body/construction is ideal for potable water systems
Shop Bell & Gossett Pressure Reducing Valves
Taco Pressure Reducing Valves
The Taco 3350 valve automatically feeds water to a hydronic system whenever the pressure drops below its set point. The 3350 PRV reduces incoming pressure and automatically maintains system pressure to the valve's adjustable set point. If the system pressure drops below the valve's set point, it will automatically add water. The 3350 is suitable for systems with fill pressure requirements between 10 and 50 psi and features a fast-fill button with automatic reset. The valve automatically exits the fast-fill mode once the system is full and the desired set pressure is reached.
All parts in the cartridge-style pressure-reducing valve are contained in a one-piece cartridge that can be easily removed and serviced without reducing system pressure. The device offers a fast-fill mode that automatically returns to normal mode when the set pressure is reached. It also delivers increased flow, speeding system fill times. Its unique dial-in pressure setting allows easy adjustment over the 10-50 psi range without an external gauge.
The unique one-piece cartridge design significantly reduces diaphragm load, extending the overall product life. A stainless steel coaxial strainer prevents system debris from affecting the valves' performance. An integral check valve allows the cartridge to be removed under system pressure for replacement or servicing. The 3350's body is made of forged brass. Wetted parts inside the cartridge are made of stainless steel, engineered plastics, and bronze.
Shop Taco Pressure Reducing Valves
Armstrong Pressure Reducing Valves
Armstrong low-pressure reducing valves feature the same unit as Armstrong combination valves. All working parts are brass with an easily cleaned built-in strainer. They are factory-set to 12 lbs and suitable for 1-, 2-, and 3-story buildings. Model RD-11 is equipped with either a sweat or threaded tailpiece on the inlet side and an integral check valve.
Armstrong high-pressure reducing valves are factory adjusted for 150 lbs initial and 45 lbs delivery pressure. They feature all working parts, brass, a built-in strainer, an extra-large diaphragm, and a check valve.
Shop Armstrong Pressure Reducing Valves
Frequently Asked Questions
A PRV reduces high inlet pressure to a safe, consistent outlet pressure in closed-loop systems.
Typically installed at the main water line or upstream of sensitive equipment.
By turning the adjustment screw (for the most common type) to increase or decrease downstream pressure.
Typically 5–15 years depending on water quality, usage, and maintenance frequency.
Pressure Reducing Valves Available in Liberty Supply
Check The PRV Ranges Available
Liberty Supply is a customer-centric organization. We focus on hydronic and steam systems for commercial and industrial facilities. As a B2B distributor within the "needs business," our foundational pillars are knowledge, communication, and speed. Relationships are built through hard work and consistent delivery of value. No exceptions. Our team maintains that with each transaction, we start back at zero.
Contact Liberty Supply
For any further questions or support, don't hesitate to contact us:
- Phone: 844-448-0880
- Fax: 844-448-0881
- Email: [email protected]
