This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X425S, 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 SI125X425S
The AirTAC SI125 Standard Cylinder SI125X425S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 425mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X425S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke425 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X425S
- 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 SI125X425S
The AirTAC SI125X425S is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 425 mm stroke. It delivers 6136 N push force at 0.5 MPa through a G1/2 port. AirTAC replaced this legacy unit with the SAI125X425S, a direct sharing the exact interface, bore, stroke, force, and mounting.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure and long life. It also adds SAIL, SAIF, and BSAI lock variants the SI lacked. The -S suffix means a piston magnet for CS1-B/DS1-B sensors.
Airtac SI125 Standard Cylinder SI125X425S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X425S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X425S |
| Bore size | Ø125 mm |
| Stroke | 425 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 SAI125X425S 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 SAI125X425S 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 SI125X425S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×425 | 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 SI125X425S Is Used
Heavy Press Clamping
Secures large automotive or structural stampings with 6136 N of push force at 0.5 MPa, ensuring rigid holding during machining.
Pallet Lift Gates
Actuates heavy loading dock gates over the 425 mm stroke, requiring external guide rails to prevent rod bending under off-center loads.
Industrial Mold Ejection
Ejects dense cast molds from production lines, utilizing the 125 mm bore's 1251 kgf maximum theoretical force at 1.0 MPa.
Replacing the Airtac SI125 Standard Cylinder SI125X425S with the SAI125X425S
To replace the SI125X425S, order the SAI125X425S. Confirm the ISO 15552 mounting interface, G1/2 port (PT/G/NPT), M27x2 rod thread, and your mounting accessory. The -S magnet is present for CS1-B/DS1-B switches. Sizing both ways: a 100 mm bore gives 3927 N at 0.5 MPa, while a 160 mm bore gives 10053 N. A plain cylinder drifts on air loss; for load holding use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant. With a 425 mm stroke, use external guides to prevent rod bending and side-load damage.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X425S
- ✓ 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 SI125X425S FAQ
Yes, the SI125X425S is discontinued. The direct replacement is the AirTAC SAI125X425S. It is dimensionally interchangeable per ISO 15552, retaining the same 125 mm bore, 425 mm stroke, 6136 N force, G1/2 port, and mounting interface.
This 125 mm bore cylinder features a G1/2 air port. At 0.5 MPa it provides 6136 N push and 5734 pull force. At 0.7 MPa push is 8590 N, and at 0.9 MPa it is 11045 N. The theoretical maximum force is 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X425S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X425S replacement — usually within 7-8 hours.