This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X50S, 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 SI125X50S
The AirTAC SI125 Standard Cylinder SI125X50S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 50mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X50S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke50 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X50S
- 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 SI125X50S
The AirTAC SI125X50S is a discontinued double-acting ISO 15552 profile cylinder featuring a 125mm bore, 50mm stroke, and a G1/2 air port. Delivering 6136N push force at 0.5MPa, it is replaced by the SAI125X50S. This direct successor matches the exact ISO 15552 mounting interface, bore, stroke, output force, and port size.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. The -S suffix indicates a piston magnet for legacy CS1-B/DS1-B sensors; the SAI uses current AirTAC switches. For high heat, Viton H seals raise the temperature range to 0-150C.
Airtac SI125 Standard Cylinder SI125X50S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X50S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X50S |
| Bore size | Ø125 mm |
| Stroke | 50 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 SAI125X50S 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 SAI125X50S 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 SI125X50S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×50 | 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 SI125X50S Is Used
Heavy Press Clamping
Secures large steel plates in machining centers using 6136N of clamping force at 0.5MPa, ensuring zero movement during heavy milling operations.
Pallet Stopper Arms
Acts as a robust stopper mechanism on high-capacity conveyor lines, easily absorbing the kinetic impact of fully loaded pallets up to 313kg.
Injection Mold Ejection
Provides the heavy push force required to eject dense molded components from industrial tooling, utilizing the adjustable 40mm air cushions for smooth stops.
Replacing the Airtac SI125 Standard Cylinder SI125X50S with the SAI125X50S
To replace the SI125X50S, order the SAI125X50S. Verify the ISO 15552 mounting interface, G1/2 port (PT/G/NPT thread), M27x2 rod thread, and mounting accessory. The -S magnet enables CS1-B/DS1-B sensors. For sizing both ways: a 100mm bore yields 3927N push at 0.5MPa, while a 160mm bore yields 10053N. 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 variants. The 32mm rod and 40mm cushions handle the 30-500mm/s speed range.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X50S
- ✓ 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 SI125X50S FAQ
Yes, the SI125X50S is discontinued. The direct replacement is the SAI125X50S. It shares the identical ISO 15552 mounting interface, 125mm bore, 50mm stroke, G1/2 port, and output force, fitting existing fixtures perfectly.
The 125mm bore features a G1/2 air port and M27x2 rod thread. Force ratings are: 6136N push and 5734N pull at 0.5MPa, 8590N push at 0.7MPa, 11045N push at 0.9MPa, and a theoretical max of 1251kgf at 1.0MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X50S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X50S replacement — usually within 7-8 hours.