Flow regulators made of plastic for pneumatic standard applications

Plastic Flow Control Valves for Standard Pneumatic Applications

**Plastic flow control valves** from Parker Legris offer precise flow rate control with low weight and high chemical resistance. The polymeric materials combine **corrosion-free operation** with easy installation in confined spaces. Available in miniature and standard sizes, these valves allow for fine-tuning of supply or exhaust air in pneumatic systems, whether unidirectional or bidirectional. Typical applications include feed units, machine tools, packaging machines, as well as laboratory and testing technology, where low leakage and reproducible settings are required.

Design Principle and Materials

Plastic flow control valves usually operate on the needle or slot principle. An adjustable control element changes the free cross-section and thus the mass flow. Housings, adjustment nuts, and connection threads are predominantly made of technical polymers such as POM, PA, or special Parker Legris plastic blends that are resistant to oils, coolants, and many cleaning agents. Internal wear parts and guides can be reinforced or designed with low-friction coatings to increase service life during frequent adjustments. Elastomer seals typically consist of NBR or Viton (FKM) for higher temperature and chemical resistance; for special applications, EPDM seals are used.

Connections, Designs, and Installation Options

Plastic flow control valves are available in various connection types: screw-in threads, push-in fittings for polymer or silicone hoses, and combinations for manifold mounting. Manifold mounting variants allow for modular installation of several control valves side-by-side, saving space and simplifying pipe routing. Miniature designs reduce dead volume and are suitable for fast-switching, dynamic systems. Unidirectional flow controls are cost-effective and prevent backflow, while bidirectional valves are used in applications with changing flow direction, such as in double-acting cylinders or reversible conveying systems.

Tightness, Leakage Rates, and Performance

Parker Legris polymer flow control valves are optimized for low leakage rates. The combination of precisely fitting polymer surfaces and elastomer seals minimizes leakage and ensures constant system pressures. Important for selection is knowledge of the operating temperature, system pressure, and the media used, as these parameters determine seal selection and material design. For increased demands on tightness or media tolerance, Parker offers specialized materials and sealing systems, which are also listed in technical data sheets.

Adjustability and Operating Concepts

Adjustment options range from coarsely adjustable screws to finely adjustable micrometers with scales. For frequent adjustments, ergonomic head variants or knurled nuts are available. Adjustable stops and return springs ensure reproducible positions. For automated systems, motorized or pneumatically actuated variants are possible, which can be controlled via standardized interfaces. In safety-critical systems, a lockable adjustment or the integration of an end position contact for monitoring is recommended.

Application Cases – Structured Practical Examples

**Example 1: Packaging Machine – Speed Adjustment of Grippers**
In a production line, a Parker Legris mini flow control valve regulates the exhaust air speed at the gripper cylinder. The miniature design reduces dead volume, resulting in shorter reaction times and a higher cycle frequency. NBR seals ensure tightness at 6 bar system pressure, while push-in connections enable quick service. Result: precise gripping cycles with minimal air consumption. **Example 2: Laboratory Test Bench – Fine Control of Compressed Air Volumes**
On a test bench, a bidirectional polymer flow control valve is used to enable a wide variety of test cycles with changing flow direction. FKM seals ensure resistance to experimental media and temperature fluctuations. The micrometer scale allows for reproducible settings for repeatable measurement results. Documentation of setting values accelerates the reproducibility of test procedures. **Example 3: Conveyor Technology – Manifold Mounting for Line Control**
Several flow control valves in manifold mounting control the supply rates of individual conveyor segments. Plastic housings reduce weight and installation effort. The use of EPDM seals protects against moisture and cleaning chemicals. Manifold mounting enables short pipe lengths and centralized maintenance points.

Selection Criteria – What to Consider When Ordering

Select the valve based on maximum operating pressure, desired flow range, ambient temperature, compatibility of sealing materials with the medium, and connection type. Also consider installation space, maintenance access, and whether unidirectional or bidirectional control is required. For automated systems, check the availability of electrical or pneumatic actuators and scalability through manifold mounting. * Max. operating pressure, flow characteristic, media temperature, sealing material, connection type, design (miniature/standard), directional function (uni/bi), manifold mounting capability

Maintenance, Testing, and Service Life

Maintenance intervals depend on the number of cycles and environmental influences. Regular visual inspection for wear on the adjusting spring, seals, and connections is required. Seals can be replaced with minimal tools on Parker Legris models. For high cycle numbers or abrasive media, a reinforced design or an alternative material package is recommended. Functional tests with compressed air and leak testing procedures ensure operational safety before commissioning.

Safety and Application Guidelines

Use only approved media and check the temperature and pressure specifications from the data sheet. For manifold mounting, backflow and counterflow must be considered, especially if unidirectional flow controls are installed. When used in potentially explosive atmospheres, observe the suitability of the materials and any required certifications. Parker Legris installation instructions and internal test protocols should be applied before series commissioning. Further technical information can be found under Technik on our website.

Integration into Existing Systems and Compatibility

Plastic flow control valves can be easily integrated into existing pneumatic piping networks, provided that connection sizes and pressure ranges are compatible. Push-in systems facilitate retrofitting without special tools. Pay attention to the difference between metric and imperial threads and to compatibility with pneumatic fittings from other manufacturers. Parker Legris modules are often designed for standard connections, thus offering high compatibility in industrial applications.

Procurement, Spare Parts, and Technical Data Sheets

Parker Legris flow control valves are available as individual components and in assemblies. Replacement seals and adjustment caps can be easily reordered. Technical data sheets contain characteristic curves, temperature ranges, material specifications, and wear information. Use our product pages in the shop or contact technical support for customized recommendations. Further real-world application examples can be found under Anwendungsbeispiele.

FAQ

**Which seal is suitable for aggressive cleaning media?**
For aggressive cleaning media, Viton (FKM) or PTFE-integrated sealing systems are recommended; EPDM is unsuitable for mineral oils and certain solvents. **Can a plastic flow control valve be used in high-pressure applications?**
Polymer flow controls are generally designed for medium pressures (typically up to 10–12 bar); for higher-stressed systems, metallic valves or special high-pressure versions are required. Check the data sheet for the respective type. **How does the design (miniature vs. standard) affect control accuracy?**
Miniature designs reduce dead volume and improve reaction time, but can be limited in the linear control range at very high flow rates. Choose the design based on maximum flow rate and desired fine resolution.