This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125BX250S, 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 SI125BX250S
The AirTAC SI125 Standard Cylinder SI125BX250S 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 SAI125BX250S, 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 → SAI125BX250S
- 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 SI125BX250S
The AirTAC SI125BX250S is a discontinued double-acting ISO 15552 profile cylinder featuring a 125mm bore, 250mm stroke, and a SUS304 stainless steel piston rod. It delivers 6136 N push force at 0.5 MPa via its G1/2 port. AirTAC replaced this legacy unit with the SAI125BX250S, a direct upgrade retaining the exact ISO 15552 mounting interface, bore, stroke, and output force.
The SAI upgrade features a modernized piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. The SAI family also introduces lock and clamp variants (SAIL, BSAI) absent in the SI line. This -S model includes a piston magnet for legacy CS1-B/DS1-B sensors.
Airtac SI125 Standard Cylinder SI125BX250S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125BX250S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125BX250S |
| 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 SAI125BX250S 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 SAI125BX250S 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 SI125BX250S
| 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 SI125BX250S Is Used
Heavy Stamping Press
Drives large heavy-duty stamping dies requiring high thrust, utilizing the 6136 N push force at 0.5 MPa to form thick metal components reliably.
Bulk Material Divertor
Actuates heavy lane diverters on high-capacity conveyor lines, moving bulky goods with the robust 32mm SUS304 stainless piston rod resisting corrosion.
Replacing the Airtac SI125 Standard Cylinder SI125BX250S with the SAI125BX250S
To replace the discontinued SI125BX250S, order the SAI125BX250S. Confirm the ISO 15552 mounting interface, the 125mm bore, 250mm stroke, G1/2 port, and your specific mounting accessory. The -B rod is SUS304 stainless steel, and the -S denotes a magnet for position sensing. If sizing both ways, neighboring bores offer different force classes, but at 0.5 MPa this bore yields 6136 N push and 5734 N pull. A plain cylinder drifts on air loss; the cushion only decelerates. For load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variants. For this 250mm stroke, ensure guide support to prevent rod bending and side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125BX250S
- ✓ 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 SI125BX250S FAQ
Yes, the SI125BX250S is discontinued. The direct replacement is the SAI125BX250S. It features the same ISO 15552 mounting interface, 125mm bore, 250mm stroke, G1/2 port, and force ratings, but upgrades the piston seal to two Y-shaped one-way elements for longer life.
The 125mm bore provides 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. Operating speed is 30-500 mm/s. It uses a G1/2 port, M27x2 rod thread, and 40mm adjustable cushions.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125BX250S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125BX250S replacement — usually within 7-8 hours.