This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125BX50S, 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 SI125BX50S
The AirTAC SI125 Standard Cylinder SI125BX50S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 50mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125BX50S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke50 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125BX50S
- 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 SI125BX50S
The AirTAC SI125BX50S is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 50 mm stroke. It features a SUS304 stainless piston rod and generates 6136 N push force at 0.5 MPa. The direct replacement is the SAI125BX50S, which maintains the exact ISO 15552 mounting interface, G1/2 port, and 1251 kgf maximum force.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. The SAI family also adds SAIL, SAIF, and BSAI lock variants the SI lacked.
Airtac SI125 Standard Cylinder SI125BX50S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125BX50S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125BX50S |
| Bore size | Ø125 mm |
| Stroke | 50 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 SAI125BX50S 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 SAI125BX50S 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 SI125BX50S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×50 | 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 SI125BX50S Is Used
Heavy Pressing
Drives robust pressing and stamping operations requiring up to 8590 N of thrust at 0.7 MPa.
Pallet Handling
Actuates heavy pallet stops and lifts in distribution hubs, safely moving 313 kg vertical loads.
Clamp Fixtures
Secures large machining fixtures, utilising the SUS304 rod for wash-down and corrosive resistance.
Replacing the Airtac SI125 Standard Cylinder SI125BX50S with the SAI125BX50S
To replace the SI125BX50S, order the SAI125BX50S. Confirm the ISO 15552 mounting interface, the 50 mm stroke, the G1/2 port, and the -S magnet for legacy CS1-B/DS1-B sensors (the SAI uses current AirTAC switches). If you need to size both ways, neighbouring bores offer different force classes, but at 0.5 MPa this 125 mm bore delivers 6136 N push and 5734 N pull. Remember that a plain cylinder does not hold load on air loss—the cushion only decelerates. For load holding, consider an external rod lock, a pilot check valve, or the SAIL/BSAI lock variants.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125BX50S
- ✓ 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 SI125BX50S FAQ
Yes, the SI125BX50S is discontinued. The direct replacement is the SAI125BX50S. It is dimensionally interchangeable per ISO 15552, keeping the same 125 mm bore, 50 mm stroke, G1/2 port, and mounting interface.
The G1/2 port feeds a 32 mm rod. Force output is 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 maximum theoretical 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125BX50S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125BX50S replacement — usually within 7-8 hours.