This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40AX250S, 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 SI40AX250S
The AirTAC Airtac SI40 Standard Cylinder SI40AX250S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 250mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40AX250S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke250 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40AX250S
- 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 SI40AX250S
The AirTAC SI40AX250S is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 250mm stroke. It features a SUS420J2 stainless piston rod and a built-in magnet for CS1-B/DS1-B switches. Delivering 628 N push force at 0.5 MPa via a G1/4 port, its direct replacement is the SAI40AX250S, which shares identical ISO 15552 mounting dimensions, stroke, and output force.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and extended life. The SAI family also adds SAIL, SAIF, and BSAI lock or valve variants absent in the legacy SI line.
Airtac SI40 Standard Cylinder SI40AX250S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40AX250S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40AX250S |
| Bore size | Ø40 mm |
| Stroke | 250 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 SAI40AX250S 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 SAI40AX250S 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 SI40AX250S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | 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 SI40 Standard Cylinder SI40AX250S Is Used
Stainless Rod Actuation
Leveraging the SUS420J2 rod for moderate corrosion resistance in light-duty clamping or positioning tasks within humid production areas.
Package Diverting
Pushing lightweight parcels or components across transfer lines using the 628 N push force available at 0.5 MPa operating pressure.
Replacing the Airtac SI40 Standard Cylinder SI40AX250S with the SAI40AX250S
To replace the SI40AX250S, order the SAI40AX250S. Verify your ISO 15552 mounting interface (LB, FA, TC, etc.), the 250mm stroke, G1/4 port, and the -S magnet for current AirTAC switches. The -A rod specifies SUS420J2 stainless steel for corrosion resistance. If sizing up, the 50mm bore yields 982 N push at 0.5 MPa; sizing down, the 32mm bore yields 402 N. For this 250mm stroke, ensure guide rails carry side loads to prevent rod bending. A plain cylinder drifts on air loss; for load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40AX250S
- ✓ 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 SI40AX250S FAQ
Yes, the SI40AX250S is discontinued. The direct replacement is the SAI40AX250S. It is dimensionally interchangeable per ISO 15552, retaining the same 40mm bore, 250mm stroke, G1/4 port, and mounting interface.
This double-acting cylinder uses a G1/4 air port. It generates 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 force of 128 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40AX250S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40AX250S replacement — usually within 7-8 hours.