Buy lowpriced softstart fittings by Parker Legris

Function and Benefits of Soft-Start Fittings

Soft-start fittings from Legris reduce pressure peaks when pneumatic systems start up, protecting components such as hoses, valves, and cylinders from mechanical stress. Unlike simple throttles or effective spring-return elements, soft-start fittings dampen pressure build-up in a targeted and controlled manner, thereby reducing acceleration and start-up forces. This extends the lifespan of seals, prevents leaks, and minimizes downtime due to damaged components.

Structure, Materials, and Sealing Systems

Legris soft-start fittings are typically available in nickel-plated brass or engineering polymers. Nickel-plated brass offers high mechanical strength, corrosion resistance, and temperature-stable sealing surfaces, while polymer versions provide weight advantages, chemical resistance to aggressive media, and electrical insulation. Internally, precision-machined pistons or needle valves are often used, guided in hardened metal bushings or glass-fiber reinforced plastics. Seals usually consist of NBR for general applications, FKM for higher temperatures and chemical resistance, or PTFE for media tolerance with aggressive substances.

Connections, Designs, and Installation

Soft-start fittings are available in various connection types: conical threads like BSPT/PG, cylindrical threads like BSPP/NPT, and push-in or quick-connect fittings for flexible polyurethane or nylon lines. The sealing type is crucial for selection: threaded connections with a sealing cone require torque-appropriate installation, while push-in fittings can be quickly installed without tools. Designs range from compact inline versions for confined spaces to right-angle versions for cable and hose routing. During installation, ensure clean cut edges of the hoses; for polyurethane lines, a chamfer is helpful. Screw connections with nickel-plated brass should be installed with appropriate torque and, if necessary, thread sealant to balance screw force and material stress.

Control Behavior and Adjustment Options

Soft-start fittings operate either with fixed flow restrictors or with adjustable needle valves. Fixed versions ensure reproducible start-up characteristics without the need for readjustment; adjustable models allow fine-tuning during commissioning. Typical adjustment ranges are in the low to medium square millimeter area, as even small cross-sectional changes strongly influence the control behavior. For adjustable versions, precise adjustment with a torque wrench or adjustment tool is recommended to avoid overtightening and cosmetic damage.

Thermal and Chemical Operating Conditions

When selecting, the system's operating temperature is crucial. Nickel-plated brass covers common industrial temperature ranges, while polymer versions often support low temperatures down to approximately -20 °C and high temperatures up to +80 °C or more, depending on the material class for special high-temperature plastics. Chemical resistance depends on the seal selection: NBR is suitable for oils and air, FKM for fuels and aggressive oils, PTFE for acids and bases. For special media, consultation with material data sheets or targeted material selection via our technical section is recommended: https://maku-industrie.de/technik.

Performance Criteria and Specifications

Important parameters include maximum operating pressure, permissible line capacity, reaction time during switching, and repeatability for adjustable models. Legris soft-start models are designed for typical compressed air systems up to 10 bar; special versions achieve higher pressures. Flow characteristics (Q–Δp) and leakage rating should also be checked. For design, the combination of line length, hose diameter, and valve cross-section is decisive; incorrect dimensioning can significantly limit the benefits of the soft-start fitting.

Application Areas and Practical Examples

Soft-start fittings are used wherever reduced start-up forces increase reliability: in production lines with multiple cylinders, in packaging machines, in handling technology, and in pneumatic test benches. Three structured practical examples illustrate their specific use:

• Example 1: In an assembly cell with several grippers operating in parallel, the simultaneous start-up of the cylinders leads to pressure surges, causing leaks at quick-connect fittings and premature seal wear. The use of nickel-plated brass soft-start fittings reduces the start-up flow sufficiently to significantly extend seal life and maintain stable cycle times.
• Example 2: In a packaging machine with thin-walled polyurethane hoses, start-up impulses repeatedly caused the hose ends to detach from push-in fittings. A polymer soft-start with a suitable seal improved hose routing and minimized detachment. The material combination also reduced the weight on the moving arm.
• Example 3: In a test bench for hydraulic components, pressure increases during initial filling had to be controlled to avoid measurement deviations. A high-pressure soft-start variant with an FKM seal was used here, ensuring precision in pressure build-up and eliminating measurement errors.

Integration into Existing Systems

When replacing an existing fitting, compatibility with hoses, fittings, and valves must be checked. Pay attention to nominal size and nominal pressure, as well as the sealing concept of the mating component. If necessary, adapters or intermediate pieces are useful; correct selection minimizes dead volume and improves controllability. For further installation instructions and application examples, please refer to our practical documentation: https://maku-industrie.de/anwendungsbeispiele.

Quality Assurance and Lifespan

Quality assurance begins with material certificates and ends with functional tests. Legris products undergo leak and cycle tests; relevant test parameters include leak class, switching cycles to failure, and wear at the sealing seat. In practice, regular visual inspections, isolation against dirt ingress, and occasional functional tests are part of preventive maintenance. Documented spare parts processes for seals and interchangeable inserts extend the lifespan of the fittings.

Selection Aid: Criteria at a Glance

To select the optimal soft-start fitting, check operating pressure, medium, temperature, installation space, and desired adjustability. Also consider weight, electromagnetic compatibility for sensitive applications, and ease of maintenance. We provide technical data sheets and advice on correct dimensioning.

Technical Data and Typical Connection Sizes

Typical connection sizes and standard data are:

• Connection sizes: 4 mm to 12 mm for push-in, G1/8 to G1/4 for threads. Maximum pressures: usually up to 10 bar, special versions up to 25 bar. Sealing materials: NBR, FKM, PTFE. Housing materials: nickel-plated brass, PA/PAGF (glass-fiber reinforced), engineering plastics.

Scope of Delivery, Spare Parts, and Documentation

The fitting is usually supplied including seal and adjustment element; replacement seals, adjustment wrenches, and installation instructions are available. Download technical data sheets, exploded drawings, and maintenance instructions from our technical page: https://maku-industrie.de/technik.

FAQ

1. Which seal is suitable for my application?

Choose NBR for general compressed air and oil applications, FKM for high temperatures or petrochemical exposure, and PTFE for aggressive chemicals. Check temperature range and media compatibility before selection.

2. Can I retrofit a soft-start fitting into existing lines?

Yes, if the nominal size, thread type, and operating pressure match. Pay attention to dead volume, hose routing, and correct seal installation. If in doubt, use our installation instructions at https://maku-industrie.de/technik.

3. How do I correctly adjust an adjustable soft-start fitting?

Adjust gradually in cold operating condition with the adjustment tool, measure pressure rise and cycle behavior, and then fix the setting. Document the rotation positions for reproducibility and avoid overtightening to prevent damage to seals.