Soft-Start Valves for Safe Pneumatic Start-Up

Soft-start valves to enable the gradual initial pressurisation of your system and quick exhaust by blocking the air supply to minimise system shock

SMC soft-start valves are designed to ensure a controlled and safe pressurisation of pneumatic systems during machine start-up.

By gradually increasing the air pressure, an SMC soft-start valve reduces the risk of sudden actuator movement, mechanical shock and unexpected machine behaviour.

This makes pneumatic soft-start valves an essential component in automated systems where operator safety, machine protection and energy efficiency are critical.

Why soft-start valves are used in pneumatic systems

A soft-start valve, also known as a soft-start dump valve or pneumatic soft-start valve, allows compressed air to enter the system at a low, adjustable flow rate before switching to full pressure.

This controlled sequence helps prevent rapid cylinder extension and protects downstream components from stress caused by instant pressurisation.

SMC pneumatic soft-start valves are therefore commonly used in applications involving frequent start-stop cycles or large pneumatic volumes.

Key characteristics of SMC soft-start valves

SMC soft-start valves combine controlled pneumatic start-up with key characteristics such as:

Energy-efficient valve systems with integrated noise reduction

The SMC soft start-up valve AV-A series is engineered for energy-efficient valve systems. With a very low power consumption of just 0.35 W, it supports reduced operating costs without compromising performance.

Its internal design ensures that no air is released when the main valve switches, helping to minimise compressed air losses and improve overall system efficiency.

An optional built-in silencer further reduces exhaust noise during operation.

Seamless integration with F.R.L. modular connections

Designed for flexibility in compressed air preparation, the AV-A soft start-up valve features an F.R.L. modular connection, allowing it to be easily integrated with SMC filter, regulator and lubricator units.

This modular approach simplifies installation, saves space within control panels and ensures a clean, compact pneumatic layout that meets modern machine design requirements.

High performance in demanding industrial environments

SMC soft-start dump valves support a wide operating pressure range from 0.2 to 1.0 MPa and offer high flow rates, making them suitable for a broad range of industrial applications.

The robust housing is available with an IP65-rated enclosure, providing reliable protection against dust and moisture.

This makes IP65 soft-start valves ideal for use in harsh industrial environments where durability and reliability are essential.

Why choose SMC soft-start valves

Combining controlled pressurisation, energy efficiency and robust environmental protection, SMC soft-start valves provide a dependable solution for engineers designing or upgrading pneumatic systems.

Whether used as a soft-start valve or part of a complete F.R.L. assembly, the AV-A series delivers consistent performance, improved safety and long-term operational efficiency.

Contact SMC’s expert team to discuss your soft-start valve requirements and receive tailored support for your pneumatic system design.

Frequently asked questions about soft-start valves

What is a soft-start valve?

A soft-start valve is a pneumatic valve that gradually pressurises a compressed air system during start-up. Instead of supplying full pressure instantly, it allows air to enter at a controlled, adjustable flow rate before switching to normal operating pressure, helping protect both machinery and operators.

What is the main benefit of a soft-start valve?

The primary benefit of a soft-start valve is that it prevents sudden actuator movement and mechanical shock during system start-up. By controlling the initial air supply, it reduces wear on components and extends the service life of pneumatic equipment.

How does a soft-start valve operate in a pneumatic system?

A soft-start valve initially supplies air through a low-speed, adjustable flow path, allowing downstream pressure to rise gradually. Once a predefined pressure level is reached, the valve automatically opens fully to supply normal operating flow. When the supply is shut off, the valve quickly exhausts downstream pressure to ensure safe depressurisation.

What operating pressure range do SMC soft-start valves support?

SMC soft-start valves operate within a pressure range of 0.2 to 1.0 MPa, covering the requirements of most industrial pneumatic systems.

Can the start-up speed be adjusted?

Yes. SMC soft-start valves include a flow-adjustment needle that allows engineers to fine-tune the initial air supply rate. This enables precise control of pressurisation speed based on actuator size, system volume and application requirements.