This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40BX250N, 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 SI40BX250N
The AirTAC Airtac SI40 Standard Cylinder SI40BX250N 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 SAI40BX250N, 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 → SAI40BX250N
- 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 SI40BX250N
The AirTAC SI40BX250N is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 250mm stroke. This NBR-sealed unit delivers 628N push force at 0.5MPa and uses a G1/4 port. AirTAC replaced it with the SAI40BX250N, a direct upgrade retaining the exact interface, force, and mounting dimensions.
The SAI replacement features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure. This SKU has a SUS304 stainless rod and no magnet, meaning it cannot accept a sensor.
Airtac SI40 Standard Cylinder SI40BX250N Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40BX250N |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40BX250N |
| 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 SAI40BX250N 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 SAI40BX250N 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 SI40BX250N
| 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 SI40BX250N Is Used
Package Diversion
Actuates routing gates on packaging lines using its 628N push force and 250mm travel to redirect cartons efficiently.
Stainless Rod Clamping
Secures moisture-exposed workpieces in machining fixtures, leveraging the SUS304 rod for corrosion resistance.
Vertical Lift Stops
Raises lightweight material stops up to 32kg in storage systems, operating reliably within the 30-800mm/s range.
Replacing the Airtac SI40 Standard Cylinder SI40BX250N with the SAI40BX250N
To replace the SI40BX250N, order the SAI40BX250N. Confirm the ISO 15552 mounting interface, 40mm bore, 250mm stroke, G1/4 port, NBR seals, and SUS304 rod. Because this SKU lacks a magnet (-S), it cannot support CS1-B/DS1-B sensors. If you need position sensing, select an SAI40X250S model. For sizing, a 32mm bore yields 402N push at 0.5MPa, while a 50mm bore yields 982N. At 250mm stroke, ensure guide alignment to prevent rod bending and side-load wear. Note that this plain cylinder does not hold load without air; use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant for secure holding.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40BX250N
- ✓ 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 SI40BX250N FAQ
Yes, the SI40BX250N is discontinued. The direct replacement is the SAI40BX250N. It is dimensionally interchangeable per ISO 15552, retaining the same 40mm bore, 250mm stroke, G1/4 port, and mounting interface.
This double-acting cylinder features a G1/4 port. It provides 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.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40BX250N
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40BX250N replacement — usually within 7-8 hours.