Pressure Relief Valves
Verified by Mel Sykes, Industrial Supply Chain Specialist - April 2026
| Specification | Details |
|---|---|
| Types | Spring loaded, pilot operated, safety valve |
| Set pressures | 0.5 bar to 400 bar |
| Standards | BS EN ISO 4126, API 520/526 |
| Applications | Boilers, pressure vessels, hydraulic systems, compressors |
What are Pressure Relief Valves?
Pressure Relief Valves (PRVs) are safety devices designed to protect equipment and piping systems from overpressure by releasing fluid or gas when pressure exceeds a preset level. They automatically reset once the system pressure drops below the set point.
Types and Variants
Spring Loaded PRV: This type uses a spring-loaded mechanism to open at a specific set pressure. Common sizes range from 1/4" to 2" NPT, with pressures up to 30 bar. Spring loaded PRVs are ideal for low flow rate applications due to their simple design and quick response.
Pilot Operated PRV: Pilot operated valves use an external pilot valve to sense the pressure and operate a larger main valve. These can handle higher pressures (up to 400 bar) and are used in systems with fluctuating pressures or high flow rates. They typically come in sizes from 1/2" to 6" NPT.
Safety Valve: Safety valves are similar to PRVs but designed for critical applications, like boilers and pressure vessels. These valves have higher set points (up to 400 bar) and larger discharge capacities, making them suitable for high-pressure systems. Common sizes range from 1/2" to 6" NPT.
Materials and Specifications
Pressure Relief Valves are available in various materials to meet specific application needs:
- Stainless Steel: Grades like A2-70 stainless steel ensure durability against corrosion and high temperatures.
- Carbon Steel: EN8 carbon steel is used for lower pressure applications where weight and cost are considerations.
- Bronze: Suitable for moderate temperature, non-corrosive environments.
Standards such as BS EN ISO 4126 and API 520/526 dictate the design and testing of PRVs to ensure safety and reliability. These standards cover aspects like pressure ratings, flow capacity, and material specifications.
Selection Criteria
Choosing the right Pressure Relief Valve involves several key factors:
- System Requirements: Identify the maximum operating pressure, temperature range, and fluid type.
- Set Point Accuracy: Ensure that the valve opens at a precise set point to prevent false tripping or insufficient protection.
- Flow Rate: Consider the flow rate required by your system to avoid backpressure issues.
- Mounting Position: Vertical, horizontal, or inline mounting can affect performance and installation ease.
UK Suppliers
MLC lists verified suppliers from Companies House, providing a reliable source for PRVs. Suppliers include reputable companies like CBM, BIAFD, BTMA, and BPMA members who adhere to industry standards and offer quality products.
Common Applications
Pressure Relief Valves are used across various industries:
- Boilers: Protect steam boilers by preventing overpressure.
- Pressure Vessels: Ensure safety in chemical processing plants where vessels contain high-pressure fluids.
- Hydraulic Systems: Prevent excessive pressure build-up in hydraulic machinery.
- Compressors: Safeguard compressors and air receivers from overpressure conditions.
Each application requires careful selection to match the specific needs of the system, ensuring both equipment protection and operational safety.
References
Verified UK Suppliers
| Company | Company No. | Location |
|---|---|---|
| Hayward Tyler Limited | 03450138 | 1 Kimpton Road, Luton, Bedfordshire, LU1 3LD |
| Fohen Limited | 11858967 | Fourth Floor Abbots House, Abbey Street, Reading, |
| Tmh Trading Limited | 11493534 | 2 Michaels Court Hanney Road, Southmoor, Abingdon, |
| Rotaflow Fv Limited | 01851533 | Rotec House, Bingswood Ind. Est., Whaley Bridge, H |
| Rotaflow Group Limited | 08368595 | Rotec House Bingswood Trading Estate, Whaley Bridg |
Frequently Asked Questions
What are Pressure Relief Valves?
Pressure Relief Valves are engineering components used in industrial applications. Browse verified UK suppliers on MLC.
Where can I buy Pressure Relief Valves in the UK?
MLC lists verified UK pressure relief valves suppliers with Companies House data. Browse by product category or search by location.
What are Pressure Relief Valves used for in industrial applications?
Pressure Relief Valves (PRVs) are safety devices designed to protect equipment and piping systems from overpressure by releasing fluid or gas when pressure exceeds a preset level. They're commonly found in boilers, pressure vessels, hydraulic systems, and compressors.
What types of Pressure Relief Valves are available according to the specifications?
The main types include spring-loaded PRVs, which use a spring mechanism to open at a specific set pressure, and pilot-operated PRVs, which sense pressure through an external pilot valve and operate a larger main valve. Spring loaded PRVs range from 1/4" to 2" NPT sizes with pressures up to 30 bar.
How do you choose the right Pressure Relief Valve for your application?
When selecting a PRV, consider factors such as set pressure requirements (from 0.5 bar to 400 bar), flow rate needs, and system compatibility with materials like brass or stainless steel. Additionally, ensure compliance with relevant standards.
What are the standard specifications that Pressure Relief Valves must meet in the UK?
PRVs must adhere to BS EN ISO 4126 and API 520/526 standards to guarantee quality and safety for industrial applications.
Where can I find reputable UK suppliers of Pressure Relief Valves?
Reputable UK suppliers include companies listed on mlc.org.uk, which offer a range of PRVs that meet industry standards. Verify supplier credentials by checking product compliance with BS EN ISO 4126 and API 520/526.
What are the typical cost factors for purchasing Pressure Relief Valves in the UK?
Costs can vary based on valve type (spring-loaded or pilot-operated), material, set pressure range, and certification standards. Spring-loaded PRVs tend to be less expensive than pilot-operated ones but may not handle as high a pressure.
What are some common applications for Pressure Relief Valves in the UK?
Common applications include protecting boilers, pressure vessels, hydraulic systems, and compressors from overpressure. Each application requires specific types of PRVs based on system requirements and safety standards.
How do Pressure Relief Valves ensure safety in industrial environments?
Pressure Relief Valves automatically open to release excess pressure when it exceeds a preset level, preventing equipment damage or failure due to excessive internal pressures. They reset once the system pressure drops below this set point, ensuring continuous operation and safety compliance.