This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40BX550S, 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 SI40BX550S
The AirTAC Airtac SI40 Standard Cylinder SI40BX550S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 550mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40BX550S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke550 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40BX550S
- 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 SI40BX550S
The AirTAC SI40BX550S is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 550mm stroke. Built with an extruded aluminum barrel and a SUS304 stainless piston rod, it delivers 628 N push force at 0.5 MPa through a G1/4 port. AirTAC replaced this legacy unit with the SAI40BX550S, a direct upgrade retaining the exact ISO 15552 mounting interface, bore, stroke, and port size.
The SAI replacement features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. This SI unit includes a piston magnet for legacy CS1-B/DS1-B sensors, while the SAI family introduces lock and valve variants like SAIL and BSAI that the original line lacked.
Airtac SI40 Standard Cylinder SI40BX550S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40BX550S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40BX550S |
| Bore size | Ø40 mm |
| Stroke | 550 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 SAI40BX550S 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 SAI40BX550S 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 SI40BX550S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | 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 SI40 Standard Cylinder SI40BX550S Is Used
Vertical Material Lift
Lowers and raises 30 kg platens using the 628 N push force at 0.5 MPa, requiring an external pilot check valve to prevent drift during air loss.
Sorting Diverter
Pushes packages across belts with a 550mm reach, relying on the adjustable 27mm air cushions to decelerate the rod smoothly at cycle end.
Lab Washdown Station
Actuates cleaning fixtures in humid environments using the SUS304 stainless rod option, with Viton H seals available for temperatures up to 150 C.
Replacing the Airtac SI40 Standard Cylinder SI40BX550S with the SAI40BX550S
To replace the SI40BX550S, order the SAI40BX550S. Confirm the ISO 15552 mounting interface, the 40mm bore, the 550mm stroke, the G1/4 port, and the -S magnet for sensor switching. If downsizing, a 32mm bore yields 402 N push at 0.5 MPa; if upsizing, a 50mm bore provides 982 N. A plain cylinder does not hold load without live air, as the cushion only decelerates—use an external rod lock or pilot check valve for secure holding, or specify a SAIL/BSAI lock variant. Because the 550mm stroke exceeds 300mm, prevent rod bending by guiding the load externally to avoid side-load damage. The -B rod material specifies SUS304 stainless steel, and the SAI direct uses current AirTAC switches instead of the legacy CS1-B/DS1-B set.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40BX550S
- ✓ 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 SI40BX550S FAQ
Yes, the SI40BX550S is discontinued. The direct replacement is the SAI40BX550S. It shares the identical ISO 15552 mounting interface, 40mm bore, 550mm stroke, output force, and G1/4 port, fitting existing fixtures perfectly while upgrading the piston seal.
The bore is 40mm with a G1/4 air port and an 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 is 30-800 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40BX550S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40BX550S replacement — usually within 7-8 hours.