SMC Silencer Selection: AN vs AN□02 vs ANA1 vs ANB1 Compared
2026-11-13Exhaust silencers are usually the last thing added to a pneumatic machine, and they are often chosen by thread size alone. That is how you end up with a cylinder that suddenly runs slower, or a “high noise reduction” silencer that barely changes what you hear. SMC offers several silencer series with noise reduction from the mid-teens up to 40 dB(A), and for the same port thread the effective area can differ by more than a factor of two. This guide uses only figures published in SMC’s silencer catalogue to help you pick a series by noise reduction, flow capacity, temperature and installation conditions, and to decode the part numbers.
The short answer
- The rule that matters most: SMC states that the silencer’s sonic conductance C (including the combined C of any fittings in the exhaust path) should be larger than the solenoid valve’s C. Selecting by thread alone is the usual cause of restricted exhaust and slow cylinders.
- General exhaust noise: AN05 to AN40 compact resin type, 30 dB(A), M5 and 1/8 to 1/2 male thread. The AN□-C version plugs straight onto ø4 to ø12 tubing.
- Tighter noise limits: AN202/302/402 (35 dB(A)), ANB1 (38 dB(A)) and ANA1 (40 dB(A)).
- More flow from the same port: ANB1 gives up 2 dB(A) against ANA1 but has a larger effective area at the same port size. SMC also lists it for common exhaust from manifolds.
- Small valves, pilot exhaust or higher temperatures: AN101/110/120 copper-alloy sintered (BC) elements, rated 5 to 150 °C.
- Large ports (3/4 to 2): AN500 to AN900 metal body type, 30 dB(A).
Series at a glance
All series below are rated for compressed air at a max. operating pressure of 1.0 MPa (SMC defines this as the solenoid valve inlet pressure).
| Series | Construction | Noise reduction | Connection | Temperature |
|---|---|---|---|---|
| AN05–40 | Compact resin body, resin sintered sound-absorbing element | 30 dB(A) | M5, 1/8–1/2 (R or NPT) | 5–60 °C |
| AN05–30-C | Compact resin body, one-touch fitting connection | 30 dB(A) | ø4–ø12 tube | 5–60 °C |
| AN500–900 | Metal body (aluminium alloy) | 30 dB(A) | 3/4–2 (R or NPT) | 5–60 °C |
| 25 series (2504–2511) | Zinc alloy case, exhausts in one direction | 19 dB(A) | 1/4–1 (R or NPT) | 5–60 °C |
| AN101/110/120 | Copper alloy sintered body (BC), nickel plated | 13–21 dB(A) | M3, M5, 1/8 | 5–150 °C |
| AN202/302/402 | High noise reduction, resin case | 35 dB(A) | 1/4–1/2 (R or NPT) | 5–60 °C |
| ANB1 | High noise reduction | 38 dB(A) | 1/8–1 1/2 (R only); ø6–ø10 tube | 5–60 °C |
| ANA1 | High noise reduction | 40 dB(A) | 1/8–2 (R only); ø8–ø12 tube | 5–60 °C |
A few notes from the catalogue worth knowing:
- All series can be used down to −10 °C provided there is no risk of moisture condensing and freezing.
- The AN202/302/402 case and end plates use resin equivalent to UL-94 V-0.
- The 25 series exhausts in one direction only, which keeps mist and noise from scattering.
- BC element noise reduction depends on the model: AN101-01 16, AN110-01 21, AN120-M3 13 and AN120-M5 18 dB(A). SMC positions them for compact valves and pilot exhaust. NPT versions exist for AN101 and AN110 (AN101-N01, AN110-N01).
- SMC describes ANA1 as a silencer that keeps plant noise below 85 dB(A).
- Actual noise reduction varies with the pneumatic circuit and the pressure exhausted from the valve, so treat the catalogue values as a guide.
How to size it: compare sonic conductance
SMC gives the conversion as sonic conductance C [dm³/(s·bar)] = effective area [mm²] ÷ 5. Look up C in the solenoid valve catalogue (or the combined value if fittings and tubing sit in the exhaust path) and choose a silencer with a larger C. On a 1/4 port the spread between series is wide:
| Model (R1/4) | Effective area | Sonic conductance C | Recommended flow (0.5 MPa inlet) | Noise reduction |
|---|---|---|---|---|
| AN15-02 | 15 mm² | 3 | ≤1.0 m³/min (ANR) | 30 dB(A) |
| AN20-02 | 35 mm² | 7 | ≤3.0 m³/min (ANR) | 30 dB(A) |
| AN202-02 | 35 mm² | 7 | — | 35 dB(A) |
| ANB1-02 | 35 mm² | 7 | ≤2.7 m³/min (ANR) | 38 dB(A) |
| ANA1-02 | 15 mm² | 3 | ≤1.2 m³/min (ANR) | 40 dB(A) |
| 2504-002 | 33.9 mm² | 6.8 | ≤2.2 m³/min (ANR) | 19 dB(A) |
| 2510-002 | 17.2 mm² | 3.4 | ≤1.5 m³/min (ANR) | 19 dB(A) |
A worked example with an assumed value: if the valve catalogue lists C = 4 and the exhaust port is 1/4, then AN15-02 and ANA1-02 (C = 3) are both too small. AN20-02, AN202-02 and ANB1-02 (C = 7) all qualify, and you choose between them on the noise reduction you need. That is exactly the gap ANB1 fills: 2 dB(A) less attenuation than ANA1 in exchange for more flow from the same port.
A silencer is effectively an extra restriction on the exhaust side, which is also where a meter-out speed controller works. If you are tuning cylinder speed, see meter-out vs meter-in speed control. For reading valve flow data, see our designer’s guide to directional control valves.
Decoding the part numbers
- AN20-N02: AN series, body size 20, N = NPT thread (no symbol = R), port 02 = 1/4.
- AN20-C10: C = one-touch fitting connection, 10 = for ø10 tubing.
- AN402-04: high noise reduction AN□02 series, body size 402, 1/2 port. 302 is 3/8 and 202 is 1/4.
- ANA1-03 / ANB1-03: A1 = 40 dB(A), B1 = 38 dB(A), 03 = 3/8. C08, C10 and so on are the one-touch fitting versions. Both series are R thread only.
- 2510-002: 25 series, body size 10, port 002 = 1/4. Add N after the body size for NPT.
- AN600-10: metal body type, body size 600, 1 inch port.
Installation and maintenance
- Resin bodies: hold the unthreaded end and screw in by hand. Once it starts to feel tight, put a wrench on the hex flats and add 1/4 turn. Models without hex flats are tightened by hand; M-thread models are hand-tightened until seated, then turned no more than another 30°. Overtightening can crack the body.
- BC sintered elements: tighten with your fingers on the unthreaded end. Do not grip the sintered part with a wrench.
- Metal bodies (except BC): use a wrench on the hex flats within SMC’s torque range, for example 12–14 N·m for R1/4, 22–24 N·m for R3/8 and 28–30 N·m for R1/2.
- No pipe wrenches or pliers, and no side load on the body. If vibration loosens a silencer, apply thread adhesive and refit it.
- Do not disassemble; the element cannot be replaced. When clogging slows the exhaust, fit a new silencer. SMC asks users to check actuator operation at least once a day, as running with a clogged silencer can lead to breakage.
Also design for the failure case: a clogged silencer can block the exhaust port, so the circuit should stay safe if that happens. And a silencer is not a filter. Do not use it as one on either the pressure or vacuum side.
Troubleshooting on the shop floor
| Symptom | Likely cause | What to check |
|---|---|---|
| Cylinder slows down as soon as the silencer is fitted | Silencer C is smaller than valve C | Compare with the valve catalogue C and choose a higher-C series for the same port |
| Cylinder gets gradually slower over weeks | Clogged sound-absorbing element | Replace the silencer and check the air supply for oil and contamination |
| Still loud after switching to a high noise reduction type | The noise is not exhaust noise (piping noise, machine vibration, valve switching) | Silencers only reduce exhaust noise; look for the other source |
| Oily residue around the exhaust | Oil or oil mist in the supply air is carried out with the exhaust | SMC recommends an exhaust cleaner to recover the oil and cut noise |
| Cracked resin body | Overtightened, or fitted with a pipe wrench or pliers | Fit a new one using the method above |
Checklist before you send an RFQ
- Sonic conductance C of the valve (including fittings and tubing on the exhaust side)
- Required noise reduction: 30, 35, 38 or 40 dB(A)
- Exhaust connection: M5, R, NPT, or push-in tube
- Ambient and fluid temperature: above 60 °C only the BC elements are rated (up to 150 °C)
- Environment: SMC advises against corrosive gases, water, steam, cutting fluids, direct sunlight, radiant heat and vibration
- Common manifold exhaust? Larger flow points to ANB1 or a larger port size
Talk to us
Send the valve model, exhaust port thread, target noise reduction and operating environment to doskee@dustry.ltd and we will help you narrow down the series. You can also browse our SMC product category. If you are plugging silencers straight onto tubing, our SMC tubing selection guide may help, and for the supply side see the SMC AF/AR/AL FRL guide.
FAQ
Is the highest noise reduction silencer always the best choice?
No. On a 1/4 port, ANA1-02 offers 40 dB(A) but its C is only 3, while AN20-02 and ANB1-02 have C = 7. On a high-flow valve, ANA1-02 can restrict the exhaust.
Can I clean and reuse a clogged silencer?
SMC says not to disassemble silencers and that the element is not replaceable. If clogging slows the exhaust, replace the silencer.
Which SMC silencer handles high temperatures?
The AN101/110/120 BC sintered elements are rated 5 to 150 °C. The other series covered here are limited to 60 °C.
Will a silencer stop oil mist?
No. Oil or oil mist in the supply air is released with the exhaust. SMC recommends an exhaust cleaner for that.
Source: SMC silencer catalogue covering the AN05–40, AN05–30-C, AN500–900, 25, AN101/110/120, AN202/302/402, ANA1 and ANB1 series plus specific product precautions (AN.pdf).