This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X250FTC, 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 SI125X250FTC
The AirTAC SI125 Standard Cylinder SI125X250FTC 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 SAI125X250FTC, 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 → SAI125X250FTC
- 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 SI125X250FTC
The AirTAC SI125X250FTC is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 250 mm stroke, delivering 6136 N push force at 0.5 MPa via its G1/2 port. AirTAC replaced this legacy unit with the SAI125X250FTC, a direct upgrade retaining the exact FTC trunnion mounting interface, bore, and output force.
The SAI replacement features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and long life. Note this specific SKU lacks a magnet (-S) and cannot accept a CS1-B/DS1-B sensor.
Airtac SI125 Standard Cylinder SI125X250FTC Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X250FTC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X250FTC |
| 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 SAI125X250FTC 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 SAI125X250FTC 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 SI125X250FTC
| 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 SI125X250FTC Is Used
Heavy Press Clamping
Secures large metal castings during machining operations, utilizing the 6136 N push force at 0.5 MPa to hold components rigidly against cutting forces.
Mold Ejection Systems
Drives large injection molding ejector pins via the FTC trunnion mount, absorbing shock through the 40 mm adjustable air cushions at both ends.
Replacing the Airtac SI125 Standard Cylinder SI125X250FTC with the SAI125X250FTC
To replace the SI125X250FTC, order the SAI125X250FTC and confirm the ISO 15552 interface, 125 mm bore, 250 mm stroke, G1/2 port, and FTC trunnion mount. This non-magnetic SKU cannot take a sensor; if position detection is needed, select an SAI equivalent with the S suffix for current AirTAC switches. A plain cylinder drifts on air loss—the cushion only decelerates—so for load holding use an external pilot check valve or the SAIL/BSAI lock variants. Sizing both ways: dropping to a 100 mm bore yields 3927 N push @0.5 MPa, while a 160 mm bore offers 10053 N. At 250 mm stroke, side-load and rod-bending risks are minimal, but ensure guide alignment.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X250FTC
- ✓ 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 SI125X250FTC FAQ
Yes, the AirTAC SI125X250FTC is discontinued. The direct replacement is the SAI125X250FTC. It is dimensionally interchangeable per ISO 15552, keeping the same 125 mm bore, 250 mm stroke, G1/2 port, and FTC trunnion mount, but adds an upgraded piston seal.
The G1/2 port bore delivers a push force of 6136 N and pull of 5734 N at 0.5 MPa. At 0.7 MPa push is 8590 N, and 11045 N at 0.9 MPa. The theoretical max is 1251 kgf at 1.0 MPa, with an operating speed of 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X250FTC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X250FTC replacement — usually within 7-8 hours.