This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X20S, with the same bore, stroke, output force, port and mounting, so it fits the same application. The SAI replacement keeps the same ISO 15552 mounting interface, bore, stroke, output force and accessories, so it drops straight into existing fixtures. It is the current-production version of this cylinder with an upgraded piston seal.
Airtac SI125 Standard Cylinder SI125X20S
The AirTAC SI125 Standard Cylinder SI125X20S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 20mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X20S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke20 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X20S
- No minimum order. A single piece can be ordered.
- Ready in 3–5 business days. That is the time we take to process the order and hand it to the carrier. Transit time after that depends on the destination.
About the Airtac SI125 Standard Cylinder SI125X20S
The AirTAC SI125X20S is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 20 mm stroke, delivering 6136 N push force at 0.5 MPa. AirTAC replaced this legacy unit with the SAI125X20S, a direct replacement retaining the exact ISO 15552 mounting interface, G1/2 port, M27x2 rod thread, and 40 mm cushions.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and longevity. The SAI family also adds SAIL, SAIF, and BSAI lock variants the SI lacked. This -S unit supports legacy CS1-B/DS1-B sensors.
Airtac SI125 Standard Cylinder SI125X20S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X20S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X20S |
| Bore size | Ø125 mm |
| Stroke | 20 mm |
| Acting type | Double acting |
| Port size | G1/2 |
| Rod thread | M27×2.0 |
| Fluid | Air (filtered by 40µm element) |
|---|---|
| Operating pressure | 0.15 – 1.0 MPa |
| Proof pressure | 1.5 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 500 mm/s |
| Cushion | Adjustable, 40 mm |
| Max standard stroke | Up to 1500 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI125X20S carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø125mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 6136 N | 5734 N |
| 0.7 MPa | 8590 N | — |
| Max (@1.0 MPa) | 1251 kgf | |
The SAI125X20S produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI125 Standard Cylinder SI125X20S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×20 | Stroke length in mm. |
| -S | Optional built-in magnet for sensor position sensing. |
Legacy SI-family variants: SID (double rod), SIJ (adjustable stroke) — each maps to its SAI equivalent (SID→SAID, SIJ→SAIJ). Rod material: carbon steel (blank) / SUS420J2 (A) / SUS304 (B).
Where the Airtac SI125 Standard Cylinder SI125X20S Is Used
Heavy-Duty Pressing
Applies the 6136 N thrust at 0.5 MPa for seating large bearings or forming thick materials over a short 20 mm travel distance.
High-Force Clamping
Secures heavy welded assemblies or oversized cast parts during machining using the 125 mm bore profile barrel interface.
Short-Stroke Ejection
Ejects dense molded products from presses rapidly, utilising the 30-500 mm/s speed range and robust 32 mm piston rod.
Replacing the Airtac SI125 Standard Cylinder SI125X20S with the SAI125X20S
To replace the SI125X20S, order the SAI125X20S and verify your ISO 15552 mounting fixtures, G1/2 port, and magnet switch compatibility (current AirTAC switches replace legacy CS1-B/DS1-B). Sizing both ways: the 125 mm bore yields 6136 N push at 0.5 MPa, while the neighbouring 100 mm bore offers 3927 N. Note that a plain cylinder drifts on air loss; the cushion only decelerates. For load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant. The 20 mm stroke is well below the 1500 mm standard maximum, so rod-bending side loads are negligible.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X20S
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI125 Standard Cylinder SI125X20S FAQ
Yes, the SI125X20S is discontinued. The direct replacement is the AirTAC SAI125X20S. It is dimensionally interchangeable per ISO 15552, matching the 125 mm bore, 20 mm stroke, G1/2 port, and mounting interface.
The 125 mm bore features a G1/2 air port and a 32 mm rod. It delivers 6136 N push and 5734 N pull at 0.5 MPa, 8590 N push at 0.7 MPa, 11045 N push at 0.9 MPa, and a theoretical maximum of 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X20S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X20S replacement — usually within 7-8 hours.