Skip to content

What is a Pressure Relief Valve?

Ever seen someone pop the cork off a champagne bottle? That fizzy explosion is a result of the pressurized carbon dioxide. 

In the engineering world, when pressure builds, pressure relief valves (PRV) serve a similar purpose – albeit with a touch more sophistication. They may not be the toast of every party, but when it comes to safety, PRVs are the real MVPs. 

Let’s take a closer look at what a pressure relief valve really is and what purpose it serves:

Defining the Purpose of Pressure Relief Valves

Pressure relief valves play a role that’s both subtle and crucial. PRVs silently and diligently monitor and manage pressure, ensuring harmony in the systems they oversee. Let’s examine their purpose in the grander scheme of things: 

1. Safety:

PRVs are designed to protect equipment, the environment, and people. Their primary role is to ensure equipment, such as boilers, pipelines, and tanks, operate within their pressure limits. This not only prolongs the life of equipment but also reduces the risk of catastrophic failures.

2. Operational Integrity:iStock-1452166359

Pressure relief valves ensure equipment functions at peak performance by preventing overpressure which can hamper processes or damage the equipment. 

3. Cost-Efficiency:

Damaged equipment results in unplanned downtime and expensive repairs or replacements. By preventing overpressure situations, PRVs indirectly contribute to cost savings.

4. Environmental Protection:

Malfunctions due to overpressure can result in spills or leaks. PRVs help mitigate such environmental hazards, ensuring industries don’t unintentionally harm the environment. 

5. Compliance Adherence:

Many industries have stringent regulations and standards. PRVs are crucial in ensuring that systems and processes adhere to these regulations by maintaining the prescribed pressure limits

While their mechanism may seem simple, the role of pressure relief valves is multifaceted. They don’t just release pressure, they safeguard, optimize, and ensure the sustainability of the systems they protect

How Do Pressure Relief Valves Work?

When discussing pressure relief valves, the disc is the movable component of the valve that seals against the valve seat. When a system operates under normal pressure, the disc is held against the valve seat, creating a seal and preventing any flow through the valve. 

The disc can be pushed up (or lifted) from its seat when the pressure exceeds a set threshold, which allows the excess pressure to be vented or relieved. When the pressure returns to acceptable levels, the disc sits neatly back in place, waiting for its next moment to shine. 

3 Common Types of Pressure Relief Valves

Three of the most common types of pressure relief valves include: 

  1. Conventional spring-loaded 
  2. Balanced spring-loaded
  3. Pilot-operated 

1. Conventional Spring-Loaded Pressure Relief Valves

Conventional spring-loaded pressure relief valves are best suited for applications with no backpressure. These valves use a spring mechanism to hold the disc in place. When system pressure surpasses the set threshold (as determined by the spring tension), the valve opens, releasing the excess pressure. Once the pressure normalizes, the spring pushes the disc back into its original position, sealing the system.

2. Balanced Spring-Loaded Pressure Relief Valves

These are an upgrade from the conventional design, featuring bellows or a similar mechanism that balances out the impact of back pressure on the valve. This ensures the valve only opens when there’s an actual increase in system pressure, not just due to back pressure. 

3. Pilot-Operated Pressure Relief Valves

This design involves two valves - the main valve and a smaller, pilot valve. Instead of a spring, the main valve is held in place by system pressure against a piston or diaphragm. 

The pilot valve, on the other hand, is spring-loaded. When system pressure surpasses the designated limit, the pilot valve opens, causing the main valve to activate and release the excess pressure.

Applications of Pressure Relief Valves

Pressure relief valves are essential in many industries and applications, ensuring the safe and efficient operation of critical processes and systems. Here, we’ll explore the role of pressure relief valves in a variety of applications:

HVAC Systems: Pressure relief valves are critical components in HVAC (Heating, Ventilation, and Air Conditioning) systems. They help regulate and control the pressure within HVAC equipment such as chillers, boilers, and piping systems. These valves ensure that pressure remains within safe operating limits, preventing system damage and maintaining efficient operation.
Steam Boilers: Pressure relief valves are crucial in steam boiler systems to prevent excessive pressure buildup that can lead to explosions or equipment failure.
Fuel Tanks: Pressure relief valves are commonly used in fuel storage tanks to prevent tank rupture or damage caused by pressure fluctuations, ensuring the integrity and safety of the fuel storage system.
Piping Systems: PRVs are installed in piping systems to safeguard against pressure surges or blockages.
Hydraulic Systems: Pressure relief valves ensure the safe and controlled operation of hydraulic cylinders, pumps, and other components by releasing excessive fluid pressure.
Compressed Air Systems: PRVs are used in compressed air systems to prevent the buildup of excessive pressure that can lead to damaged equipment or leaks.
Chemical Processing: PRVs are essential in chemical processing plants to protect vessels, reactors, and pipelines from overpressure situations caused by chemical reactions or process upsets.
Refining Industry: Pressure relief valves are commonly used in refining operations to protect equipment such as distillation columns, heat exchangers, and storage tanks.
Water Supply Systems: PRVs are used in water supply systems to regulate and maintain optimal water pressure, protect pipes and fixtures from damage due to excessive pressure, and help prevent bursts or leaks. 
Refrigeration Systems: Pressure relief valves are used to protect against overpressure situations that can occur due to factors such as temperature fluctuations or system malfunctions. 

PRVs: Thriving Under Pressure

As we navigate the complexities of a world constantly under pressure, pressure relief valves serve as silent heroes, providing the peace of mind that comes with knowing that our processes, machinery, and personnel are protected. Whether it’s protecting against catastrophic explosions or safeguarding equipment from damage, pressure relief valves play a crucial role in maintaining the integrity and safety of various systems.

Have questions? Reach out to one of our experts today!

contact the metal experts