This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125AX250S, 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 SI125AX250S
The AirTAC SI125 Standard Cylinder SI125AX250S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 250mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125AX250S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke250 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125AX250S
- 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 SI125AX250S
The AirTAC SI125AX250S is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 250 mm stroke. Featuring a SUS420J2 stainless steel rod and a built-in piston magnet for CS1-B/DS1-B switches, it delivers 6136 N push force at 0.5 MPa. The direct replacement is the SAI125AX250S, matching the G1/2 port, M27x2 thread, and ISO 15552 mounting interface.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. For load holding, note the air cushion only decelerates; use a SAIL lock or external pilot check valve.
Airtac SI125 Standard Cylinder SI125AX250S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125AX250S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125AX250S |
| Bore size | Ø125 mm |
| Stroke | 250 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 SAI125AX250S 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 SAI125AX250S 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 SI125AX250S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×250 | 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 SI125AX250S Is Used
Heavy Stamping Press
Drives large platens and heavy dies in metal forming, utilizing the 6136 N push force at 0.5 MPa to form thick steel components reliably.
Injection Mold Ejector
Ejects large molded plastic parts from heavy machinery, using the 40 mm adjustable air cushions to decelerate the 32 mm rod smoothly at stroke end.
Replacing the Airtac SI125 Standard Cylinder SI125AX250S with the SAI125AX250S
To replace the SI125AX250S, order the SAI125AX250S. Verify the ISO 15552 mounting interface, 250 mm stroke, G1/2 port, and the -S magnet for current AirTAC switches. If downsizing, a 100 mm bore yields 3927 N push at 0.5 MPa; if upsizing, a 160 mm bore yields 10053 N. The 32 mm rod and M27x2 thread are retained. For loads needing hold on air loss, the plain SAI drifts; specify a SAIL air-released lock, BSAI clamp-lock, or external rod lock. At 250 mm stroke, rod bending is low, but always guide the load to prevent side-load wear. The -A rod is SUS420J2 stainless steel.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125AX250S
- ✓ 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 SI125AX250S FAQ
Yes, the SI125AX250S is discontinued. The direct replacement is the SAI125AX250S. It is dimensionally interchangeable per ISO 15552, retaining the same 125 mm bore, 250 mm stroke, G1/2 port, and mounting fixtures.
This double-acting cylinder has a G1/2 port. It delivers 6136 N push and 5734 N pull at 0.5 MPa, 8590 N push at 0.7 MPa, 11045 N at 0.9 MPa, and a theoretical max of 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125AX250S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125AX250S replacement — usually within 7-8 hours.