Flowstar is the UK’s largest stockist of pressure relief valves, offering a comprehensive range for immediate despatch. All in-stock valve orders are shipped the same day when placed before 5pm (4:30pm on Fridays), ensuring fast and reliable delivery across the UK. For resellers and businesses purchasing valves regularly, Flowstar provides competitive trade discounts on listed prices. To discuss pricing or place an order, contact our team at sales@flowstar.co.uk or call 01482 601030 today.
A relief valve is a type of pressure control valve designed to limit pressure in a system by allowing excess fluid (liquid or gas) to escape when the pressure exceeds a preset limit — thereby protecting the system from overpressure damage.
How a Relief Valve Works
- It stays closed during normal operation.
- When system pressure exceeds the setpoint, the valve gradually opens to release fluid.
- Once pressure drops back to a safe level, it closes again to maintain system integrity.
Unlike safety valves (which snap fully open), relief valves typically open proportionally to the pressure increase.
Types of Relief Valves
- Spring-Loaded Relief Valve
- Uses a spring to maintain set pressure.
- Common in hydraulic and liquid systems.
- Pilot-Operated Relief Valve
- Uses a pilot valve to control the main valve.
- Suitable for high-capacity systems requiring precise control.
- Pressure and Temperature Relief Valve (PTRV)
- Combines pressure and temperature sensing.
- Used in water heaters and thermal systems.
Applications
- Hydraulic systems
- Pumps (to prevent dead-heading or overloading)
- Compressors
- Pipelines carrying liquids
- Pressure vessels for slow or controlled relief
Relief Valve vs Safety Valve
| Feature | Relief Valve | Safety Valve |
|---|
| Activation | Gradual opening based on pressure rise | Instant, full lift at set pressure |
| Typical use | Liquids (hydraulics, water, oil) | Gases and vapors (steam, air, gas) |
| Design purpose | Process control | Emergency protection |
| Set pressure tolerance | Narrow | Wider range (to handle spikes) |
Benefits
- Prevents system damage from overpressure
- Maintains safe operating conditions
- Extends equipment life
- Essential for compliance with safety standards (e.g., ASME, API, ISO)