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Technical Information on Parker Legris Metal Exhaust Valves

Exhaust valves from Parker Legris specifically accelerate the return speed of pneumatic cylinders by controllably venting air through a direct exhaust port. The series includes versions in nickel-plated brass, stainless steel, and aluminum, in straight and L-shaped designs, and with various connection threads. These valves are designed for industrial applications requiring reproducible cycle times, compact design, and chemical resistance. Typical applications include manufacturing automation, presses, handling systems, and machine tools.

Materials, Corrosion Protection, and Suitability

Parker Legris offers exhaust valves in several metal alloys. Nickel-plated brass combines good mechanical strength with improved corrosion protection against moisture and moderate chemicals. Stainless steel (mostly AISI 303/304 or 316 depending on the product family) is used for corrosive environments, food or pharmaceutical applications, and elevated temperature requirements. Aluminum provides low weight with sufficient strength for many automation applications but is less resistant to aggressive media than stainless steel. Material selection depends on environmental conditions, cleaning cycles, and mechanical stress.

Designs, Connections, and Seals

The valves are available in straight or L-shaped designs to accommodate space requirements and installation directions. Connections include metric external threads (e.g., M5, M7) and tapered BSP or NPT variants, as well as screw-in threads for pneumatic manifold plates. Internal dimensions and bores are optimized for minimal pressure loss. Seals primarily consist of NBR for general applications; for higher temperatures or aggressive media, FKM (Viton) or EPDM variants are available. For stainless steel housings, PTFE or FKM seals are often combined to ensure chemical resistance and long service life.

Pressure and Temperature Ranges, Flow Rates

Legris exhaust valves are designed for operating pressures typically from 0–10 bar and achieve precise and fast exhaust functions when installed correctly. Temperature ranges vary with material and seal: NBR variants are usually usable up to +80 °C, FKM up to +150 °C, EPDM up to +120 °C. Flow coefficients (Cv or Kv) depend on connection size and internal bore; for cylinders with medium piston area, a sufficiently large bore is usually provided to significantly reduce the return time. Test values are product-dependent and should be taken from the technical data sheet.

Mechanics, Adjustability, and Maintenance Aspects

Many versions offer an adjustable or fixed exhaust opening. Adjustable valves use a needle nozzle or screw damping to limit the airflow, thereby preventing braking or piston impacts. Fixed-value valves provide a constant, reproducible exhaust without readjustment. Maintenance is generally limited to visual inspection, cleaning of foreign particles, and periodic seal replacement during intensive use or in aggressive media. Easy disassembly and replacement of common seal sizes reduce downtime in production.

Standard Norms, Compatibility, and Labeling

Products are generally manufactured according to industrial standards; information on thread forms, materials, and pressure ratings is stored on the valve body or in the technical data sheets. Compatibility with pneumatic hoses, quick couplings, and cylinder connections is ensured by standardized threads and dimensions. For selection, the exact matching dimension between cylinder and valve connection is crucial, as is the distinction between mounting thread and line interface.

Application and Installation Examples

Practical Example 1 – Cycle Cylinder in Assembly System: In an assembly line, a nickel-plated brass exhaust valve reduces the return delay of a 32 mm cylinder by venting air directly at the cylinder connection. The L-shaped design allows for space-saving installation in confined spaces next to guide rails. Adjusted damping minimizes piston impacts at the end stop and increases the mechanical lifespan.

Practical Example 2 – Paint Line with Corrosive Media: In a paint environment, cylindrical drives are equipped with stainless steel exhaust valves, combined with FKM seals. The stainless steel version prevents corrosion from solvent residues and cleaning agents. Direct venting at the cylinder reduces contamination of line sections and facilitates regular cleaning cycles.

Practical Example 3 – Food Packaging: In food industry packaging applications, hygienic requirements are high. Here, stainless steel valves with PTFE seals are used. The smooth surfaces and the possibility of sterilization reduce deposits. Exhaust valves improve the cycle times of filling and capping cylinders and ensure constant cycle rates.

Selection Criteria for the Right Variant

Select the valve based on operating pressure, ambient temperature, chemical exposure, installation space, and desired adjustment options. For aggressive media or humid environments, stainless steel with FKM or PTFE seals is the preferred choice. For less corrosive applications, nickel-plated brass offers a good cost-benefit ratio. Aluminum is recommended when weight and cost are dominant and no aggressive media are present. Thread standards and connection sizes must match the cylinder connection; pay attention to metric versus imperial threads, seal type, and installation depth.

• Check: Operating pressure, temperature, medium, installation conditions, connection thread, sealing material

Installation, Testing, and Maintenance

During assembly, ensure clean threads and correct tightening torques to avoid mechanical deformation or leaks. For tapered threads, use suitable sealants compatible with the valve's sealing material. After installation, leak tests at operating pressure and functional tests with the intended cylinders are recommended. Inspections should rule out particle deposits and damage; periodic seal replacement extends service life with high switching frequency or demanding environments.

Further technical information, data sheets, and application examples can be found under Technology and Application Examples. Product details and ordering information for the entire Parker Legris series are available on the category page: High-Quality Parker Legris Metal Exhaust Valves.

FAQ

1. Which seal for my application? For general pneumatics NBR; for >80 °C or aggressive media FKM; for chemicals and highest purity requirements PTFE. Medium, temperature, and cleaning requirements are decisive.

2. How do I choose the right size? Dimension according to cylinder piston area and desired return time. Important input variables are connection thread, bore diameter, and flow coefficient (Kv/Cv). Technical data sheets of the respective valve variant provide characteristic values for calculation.

3. Can I use exhaust valves in potentially explosive areas? Only specific, certified variants may be used in Ex-areas. Standard versions without Ex-certification are not suitable. For such applications, tested components and an alignment with the risk assessment are required.