Exhaust Air Flow Control with Piloted Check Function
The Festo VFOF-CE-BAH-Q6-Q6 (manufacturer ID 8193267) is a one-way flow control valve designed for precise management of exhaust air in pneumatic systems. Its primary function is to regulate the flow of air leaving an actuator or cylinder, while its integrated non-return function allows free flow in the opposite direction. This makes it particularly useful for controlling the speed of pneumatic cylinders in a controlled and repeatable manner.
What sets this valve apart is the optional piloted check valve function. When activated via a pneumatic pilot signal at port 21 (QS-6), the valve can block flow in the non-return direction, effectively locking the actuator in position. This capability is valuable in applications where intermediate stopping or holding of a load is required, such as in clamping fixtures or lifting devices. The piloted release ensures that the actuator can only move when the pilot pressure is applied, adding a layer of safety and control.
Technical Specifications and Performance Data
The VFOF-CE-BAH-Q6-Q6 operates with a manual actuation type for the flow control adjustment, while the piloted non-return function is pneumatically actuated. The valve has two QS-6 push-in fittings for the main pneumatic connections, and a QS-6 port for the pilot air. It is designed for a working pressure range of 0.2 to 10 bar (2 to 145 psi), with pilot pressure requirements between 0.2 and 1 MPa (2 to 10 bar). The valve can handle ambient and media temperatures from -10°C to 60°C, and storage temperatures from -20°C to 70°C.
Flow performance is a key consideration. In the flow control direction, the standard nominal flow rate is 240 l/min, while the non-return direction offers a higher capacity of 400 to 460 l/min. When the piloted check function is actuated, the non-return direction flow drops to 150–230 l/min, and when unactuated, it is 120–220 l/min. Switching times are fast, with an on-time of 6 ms and an off-time of 9 ms. The valve weighs just 24.6 g, making it lightweight and suitable for compact installations.
Material Quality and Environmental Suitability
Constructed with a PBT housing and cover, the valve is robust yet lightweight. The seals are made of NBR, and the sleeve is of wrought aluminum alloy, while the adjusting screw is brass. These materials are selected for durability and compatibility with standard compressed air systems. The valve is RoHS-compliant and meets LABS (PWIS) conformity to VDMA24364-B1/B2-L, which is essential for use in paint shops and other applications where silicone-free components are required.
An important feature is its ATEX certification for use in Zone 2 and Zone 22 hazardous areas. This makes the VFOF-CE-BAH-Q6-Q6 suitable for potentially explosive atmospheres, such as those found in chemical plants, paint booths, or grain handling facilities. The valve operates with compressed air per ISO 8573-1:2010 [7:4:4], and oil lubrication is permissible if needed.
Integration and Installation Considerations
The valve can be mounted in any orientation, offering flexibility in system design. The QS-6 push-in connections simplify tubing installation, reducing assembly time. The manual exhaust function is non-detenting, meaning the adjusting screw returns to its original position when released, preventing accidental changes to the flow setting. The permissible actuation torque on the adjusting screw is 1 Nm, so care should be taken not to overtighten.
When integrating this valve into a pneumatic circuit, engineers should consider the flow requirements in both directions. For exhaust air control, the valve is typically installed on the exhaust port of a cylinder. The piloted check function can be used to lock the cylinder in place when the pilot pressure is removed. This dual functionality reduces the need for separate components, saving space and simplifying the overall system.
Practical Benefits for System Designers
For engineers and procurement teams, the Festo VFOF-CE-BAH-Q6-Q6 offers a compact, versatile solution for speed control and load holding. Its ATEX approval broadens its applicability, while the lightweight construction and any-position mounting ease installation. The valve's ability to handle both flow control and piloted check functions in one unit can lead to cost savings and reduced inventory. With a wide operating pressure range and fast switching times, it is suitable for a variety of industrial automation tasks, from packaging machinery to material handling equipment.