Precise Exhaust Flow Control with Integrated Check Function
The Festo VFOF-CE-BAH-Q4-Q4 (MPN 8193268) is a one-way flow control valve engineered for pneumatic systems that require accurate speed regulation during exhaust. Its valve function is exhaust air flow control with a non-return function, meaning it meters the flow in one direction while allowing free flow in the opposite direction. This is particularly useful for controlling cylinder speeds in automation and manufacturing processes where consistent motion is critical. The valve also offers a piloted check valve as an additional function, enabling pneumatic unlocking of the non-return function when needed. With a standard nominal flow rate of 120 l/min in the flow control direction and 210 l/min in the non-return direction, it is well-suited for small-bore actuators and precise air metering tasks.
Pneumatic Piloting and Manual Override
Unlike standard flow controls, this model incorporates a pneumatic pilot port (port 21, QS-4) that allows remote actuation of the check valve function. The pilot pressure range is 2 to 10 bar (29 to 145 psi), and the valve responds with switching times of 6 ms on and 9 ms off, making it suitable for applications requiring fast, repeatable control. A manual exhaust function with non-detenting actuation is also provided, giving operators a simple way to release downstream pressure without tools. The actuation type is manual for the flow control adjustment, while the piloted non-return function is pneumatically actuated. This combination offers flexibility in both automated and semi-automated systems.
Compact, Durable Construction for Industrial Environments
Weighing only 25.1 g, the VFOF-CE-BAH-Q4-Q4 is a lightweight component that fits into tight spaces. The housing and cover are made of PBT, a robust thermoplastic, while the seals are NBR, suitable for standard compressed air applications. The sleeve is wrought aluminum alloy, and the releasing ring is POM, ensuring reliable push-in fitting performance. The adjusting screw is brass, allowing precise setting with a permissible actuation torque of 1 Nm. The valve is RoHS-compliant and meets LABS (PWIS) conformity to VDMA24364-B1/B2-L, making it suitable for use in paint shops and other sensitive environments where silicone-free materials are required.
ATEX-Certified for Hazardous Areas
One of the standout features of this valve is its explosion prevention and protection certification for Zone 2 and Zone 22 (ATEX). This makes it a viable choice for pneumatic control in potentially explosive atmospheres, such as those found in chemical processing, painting, or material handling. The operating pressure range is 0.2 to 10 bar (up to 145 psi), and the valve can operate in ambient temperatures from -10°C to 60°C, with storage from -20°C to 70°C. The mounting position is unrestricted, simplifying installation in existing layouts.
Integration and Application Considerations
When integrating the VFOF-CE-BAH-Q4-Q4 into a system, note that it uses QS-4 push-in fittings for both pneumatic connections and the pilot port, accommodating 4 mm tubing. The operating medium must be compressed air per ISO 8573-1:2010 [7:4:4], and oil lubrication is permissible if needed. The valve’s flow characteristics are detailed: in the non-return direction, the standard flow rate is 210 l/min when unactuated, but drops to 125 l/min when actuated (piloted), while the unactuated nominal flow is 115 l/min. This distinction is critical for sizing and predicting performance under different control modes. For engineers, the ability to select between flow control and piloted check functions in one valve simplifies circuit design and reduces component count. For procurement, the ATEX certification and high-quality materials ensure long-term reliability in demanding applications, minimizing maintenance and replacement cycles.