This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X250STC, 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 SI40X250STC
The AirTAC SI40 Standard Cylinder SI40X250STC 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 SAI40X250STC, 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 → SAI40X250STC
- 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 SI40X250STC
The AirTAC SI40X250STC is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 250mm stroke. Delivering 628N push force at 0.5MPa via a G1/4 port, it is directly replaced by the SAI40X250STC. This direct upgrade shares the exact ISO 15552 mounting-interface dimensions, TC trunnion mount, and output force, fitting existing fixtures perfectly.
The SAI successor features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. It also introduces SAIL, SAIF, and BSAI lock variants absent from the legacy line. The built-in magnet supports CS1-B/DS1-B sensors, while a Viton H seal option raises operating temperatures to 150C.
Airtac SI40 Standard Cylinder SI40X250STC Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X250STC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X250STC |
| 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 SAI40X250STC 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 SAI40X250STC 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 SI40X250STC
| 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 SI40X250STC Is Used
Package Diversion
Actuates routing gates on packaging lines where 628N push force easily redirects standard cartons at speeds up to 800mm/s.
Clamp Actuation
Provides reliable clamping pressure for lightweight machining fixtures, utilizing the TC trunnion to accommodate slight misalignments.
Replacing the Airtac SI40 Standard Cylinder SI40X250STC with the SAI40X250STC
To replace the SI40X250STC, order the SAI40X250STC keeping the 40mm bore, 250mm stroke, G1/4 port, TC trunnion mount, and -S magnet. The SAI accepts current AirTAC switches for the legacy CS1-B/DS1-B set. If you need more force, the 50mm bore yields 982N push at 0.5MPa; if less is required, the 32mm bore gives 402N. Because stroke exceeds 300mm? No, but at 250mm you should still verify guide support to prevent rod bending under side loads. Note that a plain cylinder drifts on air loss—the cushion only decelerates—so use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant for held loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X250STC
- ✓ 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 SI40X250STC FAQ
Yes, the SI40X250STC is discontinued. The direct replacement is the SAI40X250STC. It shares the same ISO 15552 mounting interface, 40mm bore, 250mm stroke, G1/4 port, and TC mount, fitting directly into existing setups.
The 40mm bore features a G1/4 air port and M12x1.25 rod thread. It delivers 628N push and 528N pull at 0.5MPa, 879N push at 0.7MPa, 1130N push at 0.9MPa, and a theoretical maximum force of 128kgf at 1.0MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40X250STC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X250STC replacement — usually within 7-8 hours.