This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X250S, 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 SI40X250S
The AirTAC Airtac SI40 Standard Cylinder SI40X250S 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 SAI40X250S, 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 → SAI40X250S
- 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 SI40X250S
The AirTAC SI40X250S is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 250mm stroke. It features a 16mm carbon steel rod, M12x1.25 thread, and a G1/4 air port. Generating 628N push force at 0.5MPa, it is superseded by the SAI40X250S direct replacement, which shares the exact ISO 15552 mounting interface, bore, stroke, force, port and mounting accessories.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. For applications needing load holding, the SAI family adds SAIL and BSAI lock variants the SI lacked. This -S model includes a magnet for CS1-B/DS1-B sensors.
Airtac SI40 Standard Cylinder SI40X250S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X250S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X250S |
| 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 SAI40X250S 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 SAI40X250S 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 SI40X250S
| 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 SI40X250S Is Used
Package Diverting
Pushes medium-weight cartons off a main conveyor line using 628N of push force at 0.5MPa, with the 250mm stroke clearing adjacent lanes.
Clamp Actuation
Secures aluminum extrusions during machining operations, providing reliable holding via 528N pull force while the guide rails resist side loads.
Replacing the Airtac SI40 Standard Cylinder SI40X250S with the SAI40X250S
To replace the SI40X250S, order the SAI40X250S. Verify the ISO 15552 mounting interface, 40mm bore, 250mm stroke, G1/4 port (PT/G/NPT), and mounting accessory. The -S suffix means a magnet is present for CS1-B/DS1-B switches; the SAI replacement uses current AirTAC switches. If sizing down, a 32mm bore yields 402N push at 0.5MPa; if sizing up, a 50mm bore yields 982N. A plain cylinder does not hold load on air loss—the cushion only decelerates. For held loads, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variants. At 250mm stroke, side-load and rod-bending risks are moderate; ensure guide alignment to prevent premature seal wear.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X250S
- ✓ 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 SI40X250S FAQ
Yes, the SI40X250S is discontinued. The direct replacement is the SAI40X250S. It shares the same ISO 15552 mounting interface, 40mm bore, 250mm stroke, output force, G1/4 port, and mounting accessories, fitting existing fixtures perfectly.
At 0.5MPa it provides 628N push and 528N pull force. At 0.7MPa push is 879N, and at 0.9MPa it is 1130N. The theoretical max force is 128kgf at 1.0MPa. It operates at 30-800mm/s, uses a G1/4 port, and features a 16mm rod with an M12x1.25 thread.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40X250S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X250S replacement — usually within 7-8 hours.