Reliable compressed air pressure control within your pneumatic systems
SMC’s pneumatic pressure relief valves form part of the Airline Equipment range, providing compressed air pressure relief and manual air shut-off solutions for pneumatic systems. Designed to integrate with FRL air preparation units (filter, regulator, lubricator), these valves combine reliable downstream venting with controlled air supply interruption.
The category includes two complementary solutions: the VHS Series, a manually-operated compressed air shut-off and relief valve for maintenance and intervention; and the VP Series, an automatic compressed air pressure relief valve for system-level control. Together, they support both operator-driven and automated air release within compressed air supply lines.
For valves certified to EN ISO 13849-1 (safety-related control systems up to Category 4 / PL e), see SMC’s Safety Pressure Release Valves (ISO 13849-1) range.
Pressure release valve types in the SMC range
SMC offers two different types of pneumatic pressure relief valves within this category, each fulfilling a specific function in the compressed air supply line. The VHS Series provides manual control for operators, while the VP Series provides automatic system response. The two are designed to be used together, covering both planned intervention and continuous operation.
Manual air shut-off valve (VHS Series)
The VHS Series is a manually-operated compressed air relief valve and pneumatic shut-off valve, designed to interrupt the air supply and vent downstream pressure to atmosphere. As a compressed air release valve and manual air shut-off valve, it provides operators with a reliable means of isolating sections of a pneumatic installation before intervention.
When operated, the VHS valve closes the inlet, disconnects the downstream circuit from the air supply and releases residual pressure to atmosphere. This combined function of supply isolation and air pressure release valve action makes it suitable as a manual shut-off and compressed air quick release valve for servicing, machine reconfiguration and component replacement in compressed air systems.
Key characteristics include:
- Manual shut-off of compressed air supply
- Exhaust of downstream pressure
- Lockout capability to prevent unintended reactivation during maintenance
- Visual indication of valve position
- Robust and simple mechanical design for long operational life
- Compatible with SMC FRL units and standard pneumatic installations.
The VHS Series is widely used in industrial environments where operators need a clear, reliable and physically lockable way to isolate the compressed air supply before intervention. It is not a safety-rated component under EN ISO 13849-1; it provides operational shut-off and pressure relief, separate from the certified safety architecture covered by SMC’s Safety Pressure Release Valves (ISO 13849-1) range.
Automatic pressure relief valve (VP Series)
The VP Series provides automatic compressed air pressure relief as part of pneumatic air preparation systems. When the air supply is interrupted, the valve vents downstream pressure to atmosphere, ensuring that no residual energy remains in the line. This automatic compressed air release supports predictable system depressurisation and protects pneumatic components against unexpected reactivation.
Within the Airline Equipment range, the VP valve is typically installed downstream of the regulator and upstream of the actuators, providing system-level air control. Its automatic operation makes it complementary to the manually-operated VHS valve.
Key characteristics:
- Automatic compressed air release upon supply interruption
- Consistent and reliable downstream depressurisation
- Compact integration with FRL units and air preparation systems
- Suitable for a wide range of industrial pneumatic applications.
Specific VP Series variants are also available as certified components for safety-related control systems. For valves rated to EN ISO 13849-1 (Category 2 to Category 4 / PL e), see SMC's Safety Pressure Release Valves (ISO 13849-1) range.
Complementary functions for operation and maintenance
The VP and VHS Series valves fulfil different but complementary roles within pneumatic systems.
The VP Series valve provides automatic pressure release as part of the machine’s control system, ensuring that energy is removed when required. In contrast, the VHS Series valve makes it possible to manually shut off the air supply, allowing controlled intervention during maintenance.
Together, they cover both planned manual intervention and automatic system response, giving designers a complete solution for air supply control within standard pneumatic installations.
Easy integration into pneumatic systems
Compact and easy to install, both VP and VHS Series valves can be integrated into a wide range of pneumatic systems. Their compatibility with standard air preparation units and straightforward installation simplify system design and maintenance.
The VP valve can be incorporated into systems requiring controlled exhaust, while the VHS valve can be installed at key points to allow manual shut-off and pressure release.
Reliable performance in industrial applications
SMC pressure relief valves are built for durability and consistent operation across industrial environments. The VHS and VP Series are suitable for automated machinery, assembly lines, packaging systems and any installation where compressed air must be controlled efficiently as part of the air preparation line.
Effective pressure management for safer pneumatic systems
Combining manual and automatic compressed air relief reduces the risks associated with stored pneumatic energy. By integrating SMC relief valves into your pneumatic installations, you can:
- Reduce hazards related to residual compressed air pressure
- Prevent unintended actuator movement
- Enable controlled maintenance procedures
- Improve overall system reliability.
Need help selecting the right pressure relief valve?
Our experts are on hand to help you select the most suitable pneumatic pressure relief and shut-off valves for your application. Contact us to optimise your system performance, ensure reliable operation and support safe maintenance procedures.
Frequently asked questions about pneumatic pressure relief valves
What is the difference between pneumatic pressure relief valves and safety pressure release valves?
Pneumatic pressure relief valves, such as SMC’s VHS Series and the standard VP Series, provide functional air relief and manual shut-off within the compressed air supply line. They are designed for general system control and maintenance procedures, supporting operators in safely depressurising pneumatic systems before intervention.
Safety pressure release valves are a certified component designed for safety-related control systems. They comply with EN ISO 13849-1 and the Machinery Directive 2006/42/EC, providing redundancy, monitoring and conformity up to specific Performance Levels (for example, PL e, Category 4). For applications requiring these certifications, see SMC’s Safety Pressure Release Valves (ISO 13849-1) range.
When should I use a manual air shut-off valve?
A manual air shut-off valve, such as the VHS Series, is used whenever an operator needs to interrupt the compressed air supply and release downstream residual pressure before intervention. Typical situations include:
- Servicing or maintenance of pneumatic actuators and components
- Machine reconfiguration or tooling changes
- Component replacement or repair
- Lockout / tagout procedures to prevent accidental reactivation.
The valve provides a clear, physical and lockable way to isolate the air supply and release pressure, different from automatic or solenoid-operated valves used in the system’s normal control logic.
What is the difference between the VHS and VP Series?
The VHS Series is a manually-operated compressed air shut-off and relief valve. An operator actuates it directly to interrupt the air supply and vent downstream pressure, typically for maintenance.
The VP Series is an automatic pneumatic pressure relief valve. It vents downstream pressure when the supply is interrupted as part of the system’s normal pneumatic control logic, without operator action.
The two are complementary: the VHS supports manual intervention, while the VP supports automatic system behaviour.
How do compressed air pressure relief valves integrate with FRL air preparation units?
Compressed air pressure relief valves, such as the VHS or VP Series, connect directly to standard SMC FRL units (filter, regulator, filter regulator, lubricator). They are mounted using the same modular brackets as the rest of the Airline Equipment range, allowing engineers to add relief and shut-off functions to existing air preparation lines without major modifications.
Typical placement is downstream of the regulator, ensuring that the relief or shut-off action affects the controlled-pressure portion of the system.
