This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40BX125S, 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 SI40 Standard Cylinder SI40BX125S
The AirTAC Airtac SI40 Standard Cylinder SI40BX125S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 125mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40BX125S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke125 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40BX125S
- 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 SI40 Standard Cylinder SI40BX125S
The AirTAC SI40BX125S is a discontinued double-acting ISO 15552 profile cylinder featuring a 40mm bore, 125mm stroke, and a SUS304 stainless steel piston rod. Delivering 628 N of push force at 0.5 MPa, it is superseded by the direct replacement SAI40BX125S, which matches the original G1/4 port, M12x1.25 thread, and ISO 15552 mounting dimensions exactly.
The SAI upgrade introduces a two Y-shaped one-way piston seal for lower start-up pressure and extended life. This -S variant includes a piston magnet for legacy CS1-B/DS1-B sensors, and the broader SAI family adds SAIL, SAIF, and BSAI lock variants absent from the original SI line.
Airtac SI40 Standard Cylinder SI40BX125S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40BX125S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40BX125S |
| Bore size | Ø40 mm |
| Stroke | 125 mm |
| Acting type | Double acting |
| Port size | G1/4 |
| Rod thread | M12×1.25 |
| 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 – 800 mm/s |
| Cushion | Adjustable, 27 mm |
| Max standard stroke | Up to 1200 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI40BX125S carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø40mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 628 N | 528 N |
| 0.7 MPa | 880 N | — |
| Max (@1.0 MPa) | 128 kgf | |
The SAI40BX125S produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI40 Standard Cylinder SI40BX125S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | Bore size in mm. |
| ×125 | 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 SI40 Standard Cylinder SI40BX125S Is Used
Stainless Rod Clamping
Ideal for food-grade or washdown fixture clamping where the SUS304 rod resists corrosion while providing 628 N of push force at 0.5 MPa.
Transfer Line Diversion
Handles 125mm stroke diverting arms on packaging conveyors, utilizing the adjustable 27mm air cushions to decelerate loads smoothly at cycle end.
Replacing the Airtac SI40 Standard Cylinder SI40BX125S with the SAI40BX125S
To replace the discontinued SI40BX125S, order the SAI40BX125S, confirming the ISO 15552 mounting interface, 125mm stroke, G1/4 port, and the -S magnet for current AirTAC switches. If downsizing, a 32mm bore yields 402 N push at 0.5 MPa; if upsizing, a 50mm bore provides 982 N. Note that a plain cylinder drifts on air loss as the cushion only decelerates; for load holding, specify the SAIL or BSAI lock variant, or use an external pilot check valve. The SUS304 rod suits corrosive environments, and a Viton H seal raises operating temperature to 150 C.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40BX125S
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI40 Standard Cylinder SI40BX125S FAQ
Yes, the SI40BX125S is discontinued. The direct replacement is the SAI40BX125S. It is dimensionally interchangeable per ISO 15552, matching the 40mm bore, 125mm stroke, G1/4 port, and mounting fixtures, but features an upgraded two Y-shaped one-way piston seal.
The bore is 40mm with a G1/4 air port and M12x1.25 rod thread. Force output is 628 N push and 528 N pull at 0.5 MPa, 879 N push at 0.7 MPa, 1130 N push at 0.9 MPa, and a theoretical maximum of 128 kgf at 1.0 MPa. Operating speed ranges from 30-800 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40BX125S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40BX125S replacement — usually within 7-8 hours.