back pressure regulator vs relief valve

Back Pressure Regulator vs Relief Valve: Learn How They Help Keep Your Systems Safe and Efficient

Last Updated on February 15, 2023

Maintaining the right pressure levels is essential for your fluid and gas control systems to run without a hitch. Pressure regulators and relief valves, with their sophisticated designs, help you enjoy the superior performance while keeping potential hazards at bay.

Back Pressure Regulators provide engines and other systems a layer of protection from unexpected fluctuations in input pressure or flow rate. Their resistance-based control ensures consistent, accurate pressurization for optimal performance and safeguarding against cavitation damage.

With a relief valve, systems are safeguarded against dangerous levels of over-pressurization, expelling any excess pressure that surpasses the pre-set limit.

We’ll provide a comprehensive overview of both regulators and relief valves, including how to identify their similarities and differences. With our guidance, you can find out which component is best for your specific needs.

How they work

When it comes to managing pressure in fluid control systems, back pressure regulators and relief valves are two essential devices.

Back pressure regulators (BPRs) are designed to maintain constant back pressure in a system, regardless of changes in the inlet pressure or flow rate. These devices work by controlling the flow of fluid or gas from the outlet of a system, regulating pressure by creating a resistance to flow. 

back pressure regulator

By maintaining a consistent back pressure, BPRs help ensure accurate metering of fluids, prevent cavitation and other damaging phenomena, and optimize system performance.

Relief valves, on the other hand, are designed to protect a system from over-pressurization. They work by opening up to allow fluid or gas to escape when the pressure inside a system reaches a predetermined threshold. 

By releasing excess pressure, relief valves prevent damage to equipment and the system itself and reduce the risk of dangerous or catastrophic failures.


Back pressure regulators (BPRs) and relief valves come in a variety of types, each with their own unique features and applications.

BPRs, for example, can be categorized based on their design and method of operation. The most common types of BPRs include:

  1. Spring-loaded BPRs: These devices use a spring to apply a constant force against a diaphragm or piston, creating resistance to flow and regulating back pressure. Spring-loaded BPRs are relatively simple and cost-effective, making them ideal for a wide range of applications.
  2. Dome-loaded BPRs: These BPRs use a pressure-loaded dome to provide the force needed to regulate back pressure. These are frequently employed in applications that demand accurate and consistent pressure regulation, such as chemical processing and food and beverage production.
  3. Air-loaded BPRs: These BPRs use compressed air or gas to provide the force needed to regulate back pressure. They are often used in applications that require high accuracy and repeatability, such as research and development and laboratory testing.

Relief valves, on the other hand, can be categorized based on their design, set pressure, and application. The most common types of relief valves include:

  1. Spring-loaded relief valves: These mechanisms utilize a spring to regulate the release of pressure via a relief port and are frequently employed in applications necessitating accurate and customizable pressure relief, such as pressure vessels and steam boilers.
  2. Pilot-operated relief valves: These relief valves use a pilot valve to control the opening and closing of the main valve. These mechanisms are commonly utilized in high-flow rate applications that necessitate precise pressure control, including chemical processing and oil and gas production.
  3. Safety relief valves: These are special types of relief valves that are designed to protect personnel and equipment from harm in case of a catastrophic failure. Safety relief valves are often used in high-pressure applications, such as in power generation and oil and gas production.

Overall, the type of BPR or relief valve you choose will depend on your specific application and fluid control needs. By understanding the different types of BPRs and relief valves available, you can choose the right device to optimize your system performance and safety.

Advantages and Disadvantages of Each

Back pressure regulators (BPRs) and relief valves each have their own set of advantages and disadvantages, making it important to carefully consider their respective characteristics and features when choosing the best option for a specific application.

Advantages of Back Pressure Regulators

  • Provides precise and accurate pressure control, making it ideal for processes that require constant pressure.
  • Can be used to maintain a stable pressure upstream of a pump or compressor, which can help improve system efficiency and prevent damage to equipment.
  • Can handle a wide range of flow rates and pressures, making them highly versatile in various applications.
  • They can be adjusted to suit the requirements of the process.

Disadvantages of Back Pressure Regulators

  • May cause cavitation in downstream systems when used improperly.
  • Can cause an increase in energy usage when regulating back pressure, which can lead to higher operating costs.
  • They can be complex in design, leading to higher initial costs.

Advantages of Relief Valves

  • Protects equipment from overpressure by opening and relieving excess pressure, preventing equipment damage.
  • Can handle high flow rates and pressures, making them ideal for high-pressure applications.
  • They are simple to operate and require little maintenance, leading to low operational costs.
  • Available in various sizes, making them versatile in different applications.

Disadvantages of Relief Valves

  • May not provide accurate pressure control, making it unsuitable for applications that require precise pressure regulation.
  • Relief valves can be noisy when they open, leading to issues with noise pollution.
  • May not be able to handle certain types of fluids or gases.


Proper maintenance of back pressure regulators (BPRs) and relief valves is critical for ensuring safe and efficient operation. Here are some important considerations for maintaining these types of devices:

Back Pressure Regulator Maintenance

  • Regular cleaning and inspection of internal components can help prevent blockages and buildup that could impact pressure regulation.
  • To prevent harm to internal components, it is essential to orientate the valve during installation correctly.
  • Regular calibration of the device to ensure accurate pressure control.
  • Regular replacement of worn or damaged parts, such as diaphragms, springs, and seals.

Relief Valve Maintenance

  • Regular inspection and testing to ensure the valve is operating correctly and can relieve excess pressure when necessary.
  • Ensure that the valve is installed in the correct orientation and is properly adjusted to the system’s pressure requirements.
  • Regular cleaning of the valve’s internals to prevent buildup and blockages that could impact performance.
  • Regular replacement of worn or damaged parts, such as the valve disk or spring.

It is important to note that the maintenance requirements for BPRs and relief valves may vary depending on the specific model and application. Proper maintenance can help extend the lifespan of the device, prevent leaks and system downtime, and ensure optimal performance.

Factors to consider when selecting between the two

When selecting between a back pressure regulator (BPR) and a relief valve, it is important to consider several factors to ensure that the chosen device will meet the specific requirements of the application. Some of the key factors to consider are:

Type of Fluid: The type of fluid being processed can impact the type of device chosen. Certain fluids may require specialized materials or may not be suitable for certain types of devices. For example, corrosive or viscous fluids may require a specific type of relief valve or BPR.

Pressure Range: The pressure range required for the process is an important consideration. BPRs are typically used for lower pressure applications, whereas relief valves are commonly used for high-pressure applications.

Flow Rate: The flow rate of the fluid being processed is another important factor to consider. Both BPRs and relief valves have specific flow rate ranges that they can handle, and it is important to choose a device that can handle the required flow rate.

Precision Requirements: For applications that require precise pressure control, a BPR may be the best option. Relief valves are designed to relieve excess pressure, and while they can handle high flow rates and pressures, they may not provide the precision control required for certain applications.

Environmental Considerations: Environmental factors, such as temperature and pressure fluctuations, should be considered when selecting a device. Some devices may be better suited for extreme environments, while others may require additional protective measures to maintain optimal performance.

Cost: The cost of the device is an important consideration and can be impacted by several factors, such as material costs, design complexity, and maintenance requirements.

What happens if back pressure is too high?

Back pressure is the resistance or force opposing the desired flow of fluid through pipes, leading to friction loss and pressure drop. When back pressure is too high, it can cause a variety of issues such as increased mechanical work and deterioration of equipment due to continuous use under high pressure.

 back pressure

Additionally, foreign material blocking the flow of the mobile phase can lead to increased back pressure. To prevent these issues, it is important to understand how exhaust back pressure affects your turbo system and use high-pressure back pressure regulators for applications up to 10,000 psig / 689 bar(g).

When should a back pressure valve be used?

A back pressure valve, also known as a regulator, is an important safety device that should be used in any piping system or after pressure sensitive equipment. It is designed to maintain a defined pressure upstream of its own inlet and prevent over-pressurization downstream.

Back pressure valves are typically used in recirculating loops, hot water tanks, and other applications where it is necessary to control the upstream pressure. They are also commonly used as a safety relief valve to protect personnel and equipment from potential damage due to over-pressurization.

When selecting a back pressure valve for your application, it is important to consider the size of the valve, the flow rate, and the set point of the valve.

The size of the valve should be large enough to handle the expected flow rate while providing adequate protection against over-pressurization. Additionally, you should select a set point that will keep your system within its operating parameters while still providing sufficient protection against over-pressurization.

Where should a relief valve be located?

It is important to ensure that relief valves are installed in the correct location to prevent overpressurization and potentially catastrophic failure.

Generally, relief valves should be mounted in a vertical position with the spindle upright. This ensures that the valve can open and close properly and allows for proper drainage of any condensation or liquid that may accumulate in the valve body.

Additionally, the exact location of a relief valve depends on whether it is discharging to an open or closed system. If discharging to an open system, it should be located at the highest point of the system, while if discharging to a closed system, it should be located downstream from any other equipment such as pumps or tanks.

Why is water coming out of the relief valve?

The relief valve is a safety device used to limit pressures in systems. When the pressure within the system exceeds a certain limit, the valve opens and allows water to flow from it. This occurs as a result of an excessive buildup of pressure which can cause damage to pipes and other systems components if not released.

The relief valve is mounted at a higher point than the system’s operating level, so any excess pressure will be released through it rather than overflowing and causing potential damage downstream.

Ensure Optimal Performance and Safety in Your Fluid System

Back pressure regulators and relief valves are crucial components for maintaining safe and efficient fluid systems.

While back pressure regulators ensure consistent upstream pressure, relief valves prevent overpressure and system failures. The former offers precise pressure control, while the latter is suitable for high-pressure and high-flow applications.

Selecting the right device depends on various factors, such as the type of fluid, pressure range, flow rate, and precision requirements. Environmental factors and costs should also be considered. Evaluating these factors helps ensure optimal performance and safety of the fluid system.

In summary, both back pressure regulators and relief valves have unique benefits and limitations. By understanding their differences and choosing the appropriate device, one can guarantee reliable and effective pressure regulation in their fluid system.

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