This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X218S, 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 SI125X218S
The AirTAC SI125 Standard Cylinder SI125X218S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 218mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X218S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke218 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X218S
- 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 SI125X218S
The AirTAC SI125X218S is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 218 mm stroke. It delivers 6136 N push force at 0.5 MPa via a G1/2 port. AirTAC replaced this legacy unit with the SAI125X218S, a direct sharing the same ISO 15552 mounting interface, stroke, force and accessories. Note that 218 mm is a nonstandard stroke.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure and long life. The SAI family adds SAIL, SAIF and BSAI lock variants absent in the SI line. The -S suffix means a piston magnet for CS1-B/DS1-B sensors; SAI uses current AirTAC switches. Viton H seals raise temps to 150 C.
Airtac SI125 Standard Cylinder SI125X218S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X218S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X218S |
| Bore size | Ø125 mm |
| Stroke | 218 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 SAI125X218S 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 SAI125X218S 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 SI125X218S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×218 | 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 SI125X218S Is Used
Heavy Press Operations
Drives large stamping and forming presses requiring substantial thrust, utilizing the 6136 N push force at 0.5 MPa to deform heavy materials reliably.
Pallet Handling
Indexes loaded pallets on high-capacity conveyors, where the 313 kg vertical lift capacity and robust 32 mm piston rod handle substantial weight shifts.
Automated Clamping
Secures large castings or weldments during machining, providing the rigid holding power needed for heavy industrial fabrication environments.
Replacing the Airtac SI125 Standard Cylinder SI125X218S with the SAI125X218S
To replace the SI125X218S, order the SAI125X218S. Verify the ISO 15552 mounting accessory (LB, FA, CA, TC), the G1/2 port, and the -S magnet. Sizing both ways: the 125 mm bore yields 6136 N push at 0.5 MPa (8590 N at 0.7 MPa); if lower force is acceptable, step down to a 100 mm bore (3927 N). Because 218 mm is nonstandard, expect a special build. For any stroke over 300 mm, use a guide to prevent rod bending. A plain cylinder drifts on air loss; for load holding, use the SAIL lock, BSAI clamp-lock, or an external pilot check valve.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X218S
- ✓ 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 SI125X218S FAQ
Yes, the AirTAC SI125X218S is discontinued. The direct replacement is the SAI125X218S. It shares the identical ISO 15552 mounting interface, 125 mm bore, 218 mm stroke, G1/2 port, and output force, fitting existing fixtures perfectly.
The bore is 125 mm with a G1/2 air port and M27x2 rod thread. Force ratings are: 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 max of 1251 kgf at 1.0 MPa. Speed is 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X218S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X218S replacement — usually within 7-8 hours.