Silencers by Parker Legris for compressed air systems
Legris silencers help to reduce the ambient noise in a manufacturing environment by controlling the compressed air exhausted from control valves.
0676 - Flow control silencers made of polymer
Flow control silencers made of polymer, Engineered polymer
Silencers for Parker Legris Compressed Air Systems
Silencers from **Parker Legris** reduce noise levels directly at exhaust points in compressed air systems without significantly affecting the volume flow. For industrial applications, in addition to noise reduction, maintaining flow, compatibility with standardized connections, and the chemical resistance of materials are crucial. Legris offers solutions that combine these requirements: **polyethylene** variants for light applications, sintered bronze versions for high temperature and pressure loads, and special **throttle valve silencers** for fine dosing and noise reduction in a single component.Construction and Materials
Silencers typically consist of a housing with a porous or labyrinthine insert that diffuses compressed air and converts sound energy into heat. Parker Legris primarily uses two material groups: thermoplastic materials such as **polyethylene** and metallic solutions based on **sintered bronze** or brass. Polyethylene models offer corrosion resistance and low mass; they are resistant to many cooling lubricants and simple air contaminants. Sintered bronze silencers enable a fine-pored structure with high pressure and temperature resistance, are suitable for oily or humid environments, and can be regenerated by blowing out or replacing. Housing shapes vary: cylindrical screw or push-in connections, threaded flange versions, or screw-in models with metric or BSP threads. Standard connections from Legris are often G1/8, G1/4, or G3/8; special sizes are available. Seals are predominantly NBR or FKM rings to ensure gas-tight and vibration-resistant metal penetrations. FKM is recommended for high temperatures or aggressive media; NBR is sufficient for standard compressed air and moderate temperatures.Principle of Operation and Performance
A silencer affects two system parameters: the sound level in decibels and the pressure loss or flow rate. Parker Legris develops inserts that minimize pressure loss by combining optimal porosity and flow guidance. **Throttle valve silencers** integrate an adjustable constriction that allows for fine adjustment of the volume flow while maintaining sound-absorbing properties. This is particularly useful when pneumatic cylinders or valves need to be precisely damped without requiring separate throttling devices. Three parameters are central to selection: connection size, maximum operating pressure, and permissible temperature. Typical Parker Legris models cover pressures up to 16 bar and temperatures up to approximately 80°C; sintered bronze-based versions can withstand higher temperatures and greater loads. Technical data sheets provide pressure loss curves that describe the flow rate (l/min or m³/h) as a function of the pressure differential. For precise design, identifying the average flow velocity in the exhaust air stream is important to avoid clogging and premature wear.Connections, Installation, and Maintenance
Silencers should be mounted directly at the exhaust points: on cylinder connections, control valves, or when venting pressure vessels. Installation is done via the appropriate thread, while for screw-in models, a torque must be observed to avoid damaging the seal. In case of air-side contamination or oily condensates, regular blowing out reduces particle accumulation; sintered bronze models can be cleaned by blowing out with a compressed air blast or removed and replaced. Polyethylene models are easier to replace; they should be exchanged if visible deformation or resinification of the surface occurs. Regular inspection points include: condition of the seal, visual inspection for contamination of the filter insert, measurement of pressure loss before and after the component, and noise measurement at the exhaust point. High pressure loss or increased noise levels can indicate clogging or material fatigue. For critical systems, integrating maintenance-free or easily replaceable modules is recommended to minimize downtime.Fields of Application and Industry Relevance
In the manufacturing industry, silencers reduce noise pollution at production sites, assembly lines, and test benches. In the food and packaging industry, corrosion-resistant polyethylene versions are often the first choice, while in the machine and tool industry, sintered bronze-based units dominate due to their robustness. For pneumatic handling systems with frequent switching cycles, throttled variants are useful for fine-tuning cycle rates and braking behavior. In laboratories and test benches, the combination of good flow and high sound attenuation ensures reproducible measurement results and improved occupational safety.Practical Examples
**Example 1: Assembly island with pneumatic cylinders**In an assembly line, cylinders are vented directly at end positions via push-in fittings. The use of **polyethylene silencers** with G1/8 connection reduces sound pressure by up to 20 dB(A) without noticeable pressure loss and prevents oil mist from being carried into the ambient air. Cycle times remain stable as the throttling effect is minimal. Maintenance is performed during operation by periodic blowing out. **Example 2: Machine tools with high loads**
In a manufacturing cell with a high media content and elevated temperature, **sintered bronze silencers** are installed. These tolerate condensates and lubricating oils and maintain their porosity over a long period. If necessary, the inserts can be removed and cleaned with a short blast of compressed air; replacement is possible without special tools. The result is stable pressure loss and consistent sound attenuation over several months. **Example 3: Test field with sensitive control**
**Throttle valve silencers** are used for a test station that measures pressure rise and fall with high precision. The integrated throttle allows adjustment of the exhaust air flow, ensuring reproducible venting dynamics. The noise level simultaneously decreases without the need for additional control valves. This simplifies the calibration procedure and reduces component variety.
Selection Criteria and Specification
Choose a silencer based on the following criteria:- Connection size and thread type (metric/BSP), maximum operating pressure and temperature, material compatibility with existing media, desired sound attenuation in dB(A), permissible pressure loss, and cleaning/replacement intervals.
Compatibility and Spare Parts
Virtually all Legris silencers are designed as modules with standardized threads, so that in case of wear, only the insert or the complete housing can be changed. Replacement seals are available depending on the model; for metallic versions, **FPM/FKM** seals are often recommended for higher chemical resistance. When ordering, document the exact model code, thread type, and intended use to receive suitable spare parts.Regulation and Occupational Safety
The use of silencers contributes to compliance with occupational safety limits. Measure the sound pressure in systems with many exhaust points and systematically reduce the loudest sources by selecting appropriate porosity and design. Observe local standards and operating instructions for compressed air routing and venting.FAQ
**1. How often do silencers need to be cleaned or replaced?**Intervals depend on the medium and environment; in oily or dusty environments, inspections every 1–3 months are advisable, for clean applications 6–12 months. Sintered bronze inserts can be regenerated by blowing out; damaged or clogged polyethylene models should be replaced. **2. Do silencers affect the reaction time of pneumatic components?**
Standard silencers with low throttling effect hardly change the reaction time. With integrated throttle valve silencers, a delay is intended and adjustable. Check the flow characteristics and perform functional tests for critical applications. **3. Which material is recommended for humid, oily environments?**
Sintered bronze is primarily recommended as it tolerates oily condensates and can be cleaned by blowing out. For corrosive media, special coated metal versions or suitable plastics should be considered.