SMC AN20-02 Resin Silencer R1/4 Male Thread

A small resin silencer for valve and cylinder exhaust

AN20-02 is a compact resin silencer with a male thread from the SMC AN05 to 40 series. It is screwed into the exhaust port of a solenoid valve or a cylinder to damp the burst of noise made when compressed air is released, and to stop the exhaust from blowing straight out of the port. The 20 in the code is the body size and 02 is the R1/4 port.

Besides the male-thread type, the same catalogue lists versions with a one-touch fitting (AN20-C10 and similar), so the plain AN20-02 is the one to order when the exhaust port has a female R1/4 thread. Please check the thread of your valve before ordering: the code with the letter N in front of the port size is the NPT version.

Technical specifications

What the numbers mean for selection

The effective area tells how freely air leaves the silencer. A silencer that is too small acts as a restriction on the exhaust, so the cylinder slows down and back pressure builds in the valve. The catalogue therefore gives a recommended flow, and the silencer should be chosen so that the exhaust flow of the valve or cylinder is at or below that value. For example, AN20-02 is rated for 3.0 m3/min, while the next size up, AN30-03, is rated for 5.0 m3/min.

The 30 dB(A) reduction is a catalogue figure and the catalogue itself states that it can differ with the pneumatic circuit and the exhaust pressure, so treat it as a typical value.

Fitting and care

The body is resin, and the catalogue precautions advise against over-tightening: tighten by hand to the point where the thread begins to feel tight, then use a wrench on the hexagonal flats for only a further quarter turn. Do not use the silencer where oil mist, dust or water can clog the element without checking the precautions, and replace it when the exhaust becomes restricted, because a blocked silencer slows the cylinder.

Silencers do not cure noise that comes from piping, vibration or valve switching; the catalogue says so explicitly.

Documents and quotation

The SMC silencer catalogue linked at the end of this page covers the AN series how-to-order, performance and dimension tables plus the precautions. Please confirm thread type, port size and flow before ordering. Related parts are listed under Automation Accessories. Seven Star LLC is an independent supplier and quotes the exact code on request.

How the AN20-02 Silencer Works

When a solenoid valve switches, the air in the cylinder and in the exhaust passage is released to the atmosphere in a short, fast burst. Without a silencer, that jet leaves the port at high speed and produces a sharp noise. The AN20-02 places a resin sintered sound-absorbing element in the exhaust path, inside a resin body with hexagonal flats and an R1/4 male thread. The porous element spreads the jet over a large surface area and slows it down, which reduces the exhaust noise by about 30 dB(A) according to SMC.

The silencer is designed only to reduce exhaust-air noise. SMC states that it cannot reduce noise from inside the piping, equipment vibration or valve switching, and that it does not work as a filter for either positive or negative pressure.

AN20-02 Ordering Code and Size Range

Both the AN15-02 and the AN20-02 have a 1/4 thread, but the AN20-02 has more than twice the effective area. SMC’s selection rule is that the sonic conductance of the silencer should be larger than that of the solenoid valve it is fitted to (C = effective area ÷ 5). For valves with a large exhaust flow on a 1/4 port, the AN20-02 is the safer choice. Our team can help confirm the correct ordering code for your valve.

Installation & Maintenance

• Hold the end of the body without the thread and screw it in. When the thread begins to feel tight, tighten only a further 1/4 turn with a wrench on the hexagonal flats. Do not use a pipe wrench or pliers.
• Do not apply a lateral load to the body during or after installation. If machine vibration loosens it, apply thread-locking glue and refit it.
• Do not use it where it is exposed to corrosive gases, chemicals, water, steam, cutting oil, lubricating oil, coolant, direct sunlight or radiant heat, or where foreign matter can stick to it.
• If the supply air carries oil or oil mist, SMC recommends an exhaust cleaner instead, so the oil is not dispersed into the workplace.
• Never disassemble the silencer; the sound-absorbing material is not replaceable. When clogging lowers the exhaust speed, replace the silencer. Continued operation while clogged can cause breakage.
• Design the circuit so that a clogged silencer cannot create an unsafe condition, and check actuator operation at least once a day.

Typical Applications in Oman & the GCC

The AN20-02 is fitted to R1/4 exhaust ports of solenoid valves, valve manifolds and pneumatic panels on packaging, bottling, food processing and general assembly machinery in Oman and across the GCC. Lower exhaust noise improves the working environment around machines with many valves cycling at once.

Why Source from Seven Star LLC

Seven Star LLC supplies SMC silencers, valves and pneumatic accessories across Oman and the GCC. Request a quote with the port thread and valve model, and our team can help confirm the correct ordering code.