SMC Corporation VHS40-04 Residual Pressure Release Valve

SMC VHS40-04 Residual Pressure Relief Valve is a 3-port valve from the VHS series designed to vent residual pneumatic pressure in a line after isolation, helping prevent unintended actuator movement during maintenance or tool changes. It is built to OSHA standard specifications for pressure-relief 3-port valves and includes locking holes for safe manual operation, making it suitable for lock-out/tag-out procedures in automated systems. Available configurations include single-action (VHS-D) and double-action (VHS-W-D) variants, enabling either manual bleed or automatic relief to suit different maintenance or cycle requirements. In typical automation, robotics, and tooling applications, the VHS40-04 provides controlled release of trapped air to protect personnel and equipment when lines are opened or disconnected, while preserving system readiness when relief is complete. Notably, certain VHS40-04 derivatives offer enhanced relief flow characteristics—such as the VHS40-04-D family—reflecting improved venting performance for high-cycle or fast-acting circuits. To ensure correct fit and function, verify the exact porting, connection style, and mounting options for your regional catalog and confirm the specific VHS40-04 variant (D, W-D, or other) with official SMC product data. When integrating, design the surrounding circuit to direct released air toward atmosphere or back to a reservoir per your system architecture, and always depressurize and secure the valve using its locking holes before performing any service.