This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X550SN, 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 SI125X550SN
The AirTAC SI125 Standard Cylinder SI125X550SN is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 550mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X550SN, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke550 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X550SN
- 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 SI125X550SN
The AirTAC SI125X550SN is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 550 mm stroke. It delivers 6136 N push force at 0.5 MPa via a G1/2 port. The direct replacement is the SAI125X550SN, matching the interface, stroke and force.
The SAI upgrade features two Y-shaped one-way piston seals for low start-up pressure and long life. It also adds SAIL, SAIF and BSAI variants the SI lacked. The NBR seal handles -20 to +70 C; Viton H extends to 150 C.
Airtac SI125 Standard Cylinder SI125X550SN Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X550SN |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X550SN |
| Bore size | Ø125 mm |
| Stroke | 550 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 SAI125X550SN 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 SAI125X550SN 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 SI125X550SN
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×550 | 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 SI125X550SN Is Used
Heavy Press Clamping
Secures large steel plates in a machining center using 6136 N of thrust at 0.5 MPa, with the 550 mm stroke accommodating thick workpieces.
Pallet Positioning
Pushes loaded pallets onto a transfer line; the 313 kg vertical lift capacity handles substantial weights safely.
Automated Assembly Lift
Raises heavy subassemblies to an overhead conveyor, requiring external guides to manage the side-load risks of the 550 mm stroke.
Replacing the Airtac SI125 Standard Cylinder SI125X550SN with the SAI125X550SN
To replace the SI125X550SN, order the SAI125X550SN. It drops into existing fixtures per ISO 15552 mounting dimensions, keeping the 125 mm bore, 550 mm stroke, G1/2 port and M27x2 rod thread. Confirm your mounting accessory (LB, FA, TC) and the magnet for CS1-B/DS1-B switches. If you need less force, the 100 mm bore gives 3927 N push at 0.5 MPa; if you need more, the 160 mm bore gives 10053 N. At 550 mm stroke, use an external guide to prevent rod bending and side loads. The air cushion only decelerates; for load holding on air loss, use the SAIL lock, BSAI clamp-lock, or an external pilot check valve.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X550SN
- ✓ 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 SI125X550SN FAQ
Yes, the SI125X550SN is discontinued. The direct replacement is the SAI125X550SN. It is dimensionally interchangeable per ISO 15552, offering the same 125 mm bore, 550 mm stroke, output force, G1/2 port and mounting interface.
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 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 SAI125X550SN
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X550SN replacement — usually within 7-8 hours.