This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X250SFTC, 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 SI40X250SFTC
The AirTAC Airtac SI40 Standard Cylinder SI40X250SFTC 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 SAI40X250SFTC, 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 → SAI40X250SFTC
- 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 SI40X250SFTC
The AirTAC SI40X250SFTC is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 250mm stroke. It delivers 628N push force at 0.5MPa through a G1/4 port. The direct replacement is the SAI40X250SFTC, which matches the bore, stroke, force, port, and FTC trunnion mounting interface.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. The -S magnet supports legacy CS1-B/DS1-B sensors, and you can specify Viton H seals for 0-150C heat.
Airtac SI40 Standard Cylinder SI40X250SFTC Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X250SFTC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X250SFTC |
| 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 SAI40X250SFTC 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 SAI40X250SFTC 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 SI40X250SFTC
| 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 SI40X250SFTC Is Used
Package Diversion
Drives 250mm stroke diverting arms on packaging lines, using the 628N push force at 0.5MPa to push cartons reliably without overshooting.
Clamp Actuation
Secures medium workpieces in machining fixtures, where the adjustable 27mm air cushions ensure smooth end-of-stroke deceleration.
Replacing the Airtac SI40 Standard Cylinder SI40X250SFTC with the SAI40X250SFTC
To replace the SI40X250SFTC, order the SAI40X250SFTC. Confirm the ISO 15552 FTC trunnion mount, 40mm bore, 250mm stroke, G1/4 port (PT/G/NPT thread), and the -S magnet for CS1-B/DS1-B switches. Sizing both ways: a 50mm bore gives 982N push at 0.5MPa, while dropping to 32mm yields 402N. At 250mm stroke, use a guide to prevent rod bending and side-load wear. A plain cylinder drifts on air loss—the cushion only decelerates. For load holding, use an external pilot check valve or the SAIL/BSAI lock variants.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X250SFTC
- ✓ 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 SI40X250SFTC FAQ
Yes, the SI40X250SFTC is discontinued. The direct replacement is the SAI40X250SFTC. It features the same ISO 15552 mounting interface, 40mm bore, 250mm stroke, G1/4 port, and output force, fitting existing fixtures perfectly.
The 40mm bore uses a G1/4 air port. Force ratings are: 628N push and 528N pull at 0.5MPa, 879N push at 0.7MPa, 1130N push at 0.9MPa, and a theoretical max of 128kgf at 1.0MPa. Speed is 30-800mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40X250SFTC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X250SFTC replacement — usually within 7-8 hours.