This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125BX20S, 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 SI125BX20S
The AirTAC SI125 Standard Cylinder SI125BX20S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 20mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125BX20S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke20 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125BX20S
- 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 SI125BX20S
The AirTAC SI125BX20S is a discontinued double-acting ISO 15552 profile cylinder featuring a 125 mm bore, 20 mm stroke, and a SUS304 stainless steel piston rod. It delivers 6136 N push force at 0.5 MPa. The direct replacement is the SAI125BX20S, matching the bore, stroke, G1/2 port, and ISO 15552 mounting interface.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure. The -S magnet works with legacy CS1-B/DS1-B sensors, while the SAI family adds SAIL and BSAI lock variants the SI lacked.
Airtac SI125 Standard Cylinder SI125BX20S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125BX20S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125BX20S |
| Bore size | Ø125 mm |
| Stroke | 20 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 SAI125BX20S 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 SAI125BX20S 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 SI125BX20S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×20 | 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 SI125BX20S Is Used
Heavy Press Clamping
Uses the 6136 N push force at 0.5 MPa to secure heavy steel plates in a machining fixture, leveraging the SUS304 rod for corrosion resistance in wet coolant environments.
Mold Ejection System
Provides a short 20 mm rapid ejection stroke for injection molding lines, where the robust 125 mm bore handles high stripping forces without deflection.
Replacing the Airtac SI125 Standard Cylinder SI125BX20S with the SAI125BX20S
To replace the SI125BX20S, order the SAI125BX20S to get the exact ISO 15552 mounting interface, 125 mm bore, 20 mm stroke, G1/2 port, and SUS304 rod. For sizing down, an 80 mm bore yields 2513 N push at 0.5 MPa; sizing up to 160 mm provides 10053 N. Note that a plain cylinder drifts on air loss—the cushion only decelerates. For load holding, use an external rod lock or the SAIL/BSAI variants. The SAI uses current AirTAC switches for the magnet, replacing legacy CS1-B/DS1-B units.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125BX20S
- ✓ 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 SI125BX20S FAQ
Yes, the SI125BX20S is discontinued. The direct replacement is the SAI125BX20S, which matches the 125 mm bore, 20 mm stroke, G1/2 port, SUS304 rod, and ISO 15552 mounting interface for a direct fixture fit.
It features a G1/2 port and delivers 6136 N push / 5734 N pull at 0.5 MPa, 8590 N push at 0.7 MPa, and 11045 N push at 0.9 MPa, with a theoretical max of 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125BX20S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125BX20S replacement — usually within 7-8 hours.