SMC Air Tubing Selection: TU vs TUS vs T vs TS Compared
2026-11-12Air tubing rarely gets much attention at the design stage, yet it causes a surprising number of problems on the shop floor: tubes kinking inside a cable chain, tubing softening next to a heat source, or a cylinder slowing down after a “like-for-like” tube replacement. SMC’s general-purpose range covers four series: TU polyurethane, TUS soft polyurethane, T nylon and TS soft nylon. This guide uses only figures published in SMC’s catalogues to help you choose by pressure, temperature, routing space and fluid, and to read the part numbers correctly.
The short answer
- General pneumatic piping where flexibility matters: TU polyurethane. 0.8 MPa max. at 20 °C, small bending radius, 29 colours.
- Very tight spaces: TUS soft polyurethane. 0.6 MPa max., air only. Fit a TJ inner sleeve when using One-touch fittings.
- Higher pressure or higher temperature: T nylon. T0604 is rated 3.0 MPa at 20 °C and −40 to 100 °C on air, but it is stiff and needs a larger bend radius.
- Nylon pressure rating with a bit more flexibility: TS soft nylon. TS0604 is rated 1.7 MPa at 20 °C.
Key specifications by series
| Series | Material | Max. operating pressure (20 °C) | Operating temperature | Fluid |
|---|---|---|---|---|
| TU | Polyurethane | 0.8 MPa (0.65 at 40 °C, 0.5 at 60 °C) | −20 to 60 °C (water 0 to 40 °C) | Air / water |
| TUS | Soft polyurethane | 0.6 MPa (0.6 at 40 °C, 0.4 at 60 °C) | −20 to 60 °C | Air |
| T | Nylon 12 | T0425 3.3 / T0604 3.0 / T0806–T1209 2.0 / T1613 1.6 MPa | Air −40 to 100 °C (water 0 to 70 °C) | Air / water |
| TS | Nylon 12 (soft) | TS0425 2.0 / TS0604 1.7 / other sizes 1.3 MPa | Air −40 to 100 °C (water 0 to 50 °C) | Air / water |
Nylon loses pressure rating quickly as temperature rises. At 60 °C, T0604 drops to 1.5 MPa and T0806–T1209 to 1.0 MPa; TS0604 drops to 0.85 MPa and TS0806 and larger to 0.65 MPa. For hot locations, read the value at your actual temperature rather than the 20 °C headline figure.
Same O.D., different I.D. and bend radius
Common metric sizes, in mm (O.D./I.D., minimum bending radius):
| O.D. | TU | TUS | T | TS |
|---|---|---|---|---|
| 4 | 4/2.5, R10 | 4/2.5, R8 | 4/2.5, R13 | 4/2.5, R15 |
| 6 | 6/4, R15 | 6/4, R15 | 6/4, R24 | 6/4, R23 |
| 8 | 8/5, R20 | 8/5, R15 | 8/6, R40 | 8/6, R45 |
| 10 | 10/6.5, R27 | 10/6.5, R22 | 10/7.5, R50 | 10/7.5, R55 |
| 12 | 12/8, R35 | 12/8, R29 | 12/9, R60 | 12/9, R65 |
| 16 | 16/10, R45 | – | 16/13, R100 | 16/12, R90 |
- From 8 mm up, polyurethane has the smaller bore. TU0805 has a 5 mm I.D.; T0806 has 6 mm. Swapping nylon for polyurethane of the same O.D. keeps the fittings, but the flow area shrinks, so check large-bore or high-speed cylinders.
- Bend radii are representative values at 20 °C. SMC notes that tubing kinks more easily at higher temperatures, and tubing used below the recommended radius may flatten. Leave margin.
Reading the part number
Using SMC’s own example, TU0425BU-20:
- TU: series (polyurethane tubing)
- 04: O.D. 4 mm
- 25: I.D. 2.5 mm (0604 = 6/4, 1065 = 10/6.5)
- BU: colour, blue. Common codes: B black, W white, R red, BU blue, Y yellow, G green
- 20: 20 m roll; TU is also offered in 100 m rolls
T, TS and TUS follow the same pattern, e.g. T0425B-20, TS0604W-20, TUS1065B-100. T-series 100 m rolls come in black and white only. The inch-size equivalents are TIUB, TIA and TISA.
Selection checklist
- Pressure: SMC requires operating within the lower rating of the tubing and the fitting, and surge pressure must stay below the max. operating pressure.
- Temperature: above 60 °C, only T or TS are options; polyurethane tops out at 60 °C.
- Routing: lay out bends to the radii above. For cable chains and cramped spaces, start with TU or TUS.
- Fluid: TUS is for air only. For water, check each series’ water temperature range.
- Fittings: all four series work with One-touch and insert fittings. For T and TS with metal One-touch fittings at 60 °C or above, SMC calls for an inner sleeve. For TUS in safety circuits or critical areas, always fit a TJ inner sleeve.
The sleeve makes a big difference to TUS pull-out strength (SMC catalogue values, with One-touch fittings):
| Model | Without sleeve | With TJ sleeve | Sleeve part no. |
|---|---|---|---|
| TUS0425 | 15 N | 80 N | TJ-0425 |
| TUS0604 | 60 N | 230 N | TJ-0604 |
| TUS0805 | 60 N | 250 N | TJ-0805 |
| TUS1065 | 85 N | 300 N | TJ-1065 |
| TUS1208 | 110 N | 480 N | TJ-1208 |
Troubleshooting by symptom
| Symptom | Likely cause | Check first |
|---|---|---|
| Tube flattens at a bend, cylinder slows | Bend radius below the catalogue value | Re-route, or move to TU / TUS |
| Tubing near a heat source softens or balloons | Above polyurethane’s 60 °C limit, or pressure above the derated value | Switch to T / TS and read the rating at actual temperature |
| Cylinder slower after a tube change | Same O.D., smaller I.D. (8 mm: T0806 6 mm vs TU0805 5 mm) | Compare bore and required flow |
| Soft tube pulls out of the fitting | TUS used without inner sleeve | Fit the matching TJ sleeve |
Other cautions from the catalogues
- Adiabatic compression can cause an abnormal temperature rise that may burst the tube; SMC flags this for all four series.
- When T nylon tubing carries turbine oil (class 1, ISO VG32), SMC warns that the nylon may harden over long-term use, specifies static piping only, and asks for a new tube whenever one is removed from a fitting.
- Match tube size to valve and speed-controller ports. See our guide to meter-out vs meter-in speed control, and for upstream air quality, building an SMC AF/AR/AL FRL system. A single TU size is covered in our TU0604BU-100 polyurethane tubing note.
Talk to us
Send us your working pressure, ambient temperature, tube O.D., routing (fixed or cable chain) and fluid at doskee@dustry.ltd and we will help you narrow down the series. You can also browse our SMC product category.
FAQ
What pressure can SMC polyurethane tubing handle?
TU is rated 0.8 MPa at 20 °C, 0.65 MPa at 40 °C and 0.5 MPa at 60 °C.
Can I replace TU with T nylon tubing?
Fittings are the same for the same O.D., but nylon is stiffer. From SMC’s tables, T needs about 1.3× the TU bend radius at 4 mm and roughly 1.6–2.2× at 6 mm and above, so the existing routing may not fit. Going the other way, check pressure, temperature and the smaller I.D. of TU at 8 mm and up.
Can these tubes carry water?
TU, T and TS are rated for water (0–40, 0–70 and 0–50 °C respectively). TUS is for air only.
TS or T nylon?
Both are nylon 12 with the same air temperature range. T has the higher pressure rating and TS is more pliable. At 6 mm their bend radii are close; from 8 mm up, TS is actually slightly larger, so check the table.
Sources: SMC T/TIA Series nylon tubing catalogue (T_TIA.pdf); SMC TS/TISA Series soft nylon tubing catalogue (TS_TISA.pdf); SMC Series TU/TIUB polyurethane tubing catalogue P-04-EU1Aa-UK (TU_TIUB.pdf); SMC TUS Series soft polyurethane tubing catalogue (TUS.pdf); SMC Best Pneumatics, Fittings & Tubing Series Variations (PDF).