This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40BX250, 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 SI40BX250
The AirTAC Airtac SI40 Standard Cylinder SI40BX250 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 SAI40BX250, 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 → SAI40BX250
- 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 SI40BX250
The AirTAC SI40BX250 is a discontinued double-acting ISO 15552 profile cylinder featuring a 40mm bore, 250mm stroke, and a SUS304 stainless piston rod for corrosion resistance. Delivering 628 N push force at 0.5 MPa, it is replaced by the SAI40BX250. This direct upgrade retains the exact G1/4 port, M12x1.25 thread, and ISO 15552 mounting dimensions to fit existing fixtures.
The SAI successor introduces an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. Note this non-magnetic SKU cannot accept a sensor; the legacy SI used CS1-B/DS1-B switches on magnetized versions.
Airtac SI40 Standard Cylinder SI40BX250 Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40BX250 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40BX250 |
| 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 SAI40BX250 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 SAI40BX250 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 SI40BX250
| 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 SI40BX250 Is Used
Washdown Sorting
Ideal for food or chemical conveyors where the SUS304 rod resists moisture while pushing 32 kg packages at 250mm stroke.
Light Machining Clamps
Provides reliable 628 N holding force for mid-sized aluminium fixture clamping on automated CNC cells.
Vertical Lowering
Controls the descent of light tooling heads; ensure external guides manage the 250mm stroke to avoid rod bending.
Replacing the Airtac SI40 Standard Cylinder SI40BX250 with the SAI40BX250
To replace the SI40BX250, order the SAI40BX250. Verify your ISO 15552 mounting accessory (LB, FA, TC, etc.), the G1/4 air port, and the M12x1.25 rod thread. Because this SKU lacks the -S magnet, it cannot support position sensing; if switches are needed, specify a magnet on the new SAI order. The 250mm stroke is within the 1200mm standard maximum, but strokes over 300mm require careful alignment to prevent side-load and rod-bending—use guide rails. If dropping to a 32mm bore reduces force too much (402 N push @0.5 MPa), stay with 40mm. A plain cylinder drifts on air loss; for load holding, use an external pilot check valve or specify the SAIL lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40BX250
- ✓ 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 SI40BX250 FAQ
Yes, the SI40BX250 is discontinued. The direct replacement is the SAI40BX250. It features the same ISO 15552 mounting interface, 40mm bore, 250mm stroke, output force, G1/4 port, and SUS304 stainless rod, fitting directly into your existing machine fixtures.
The bore is 40mm with a G1/4 air port and M12x1.25 rod thread. At 0.5 MPa it pushes 628 N and pulls 528 N. At 0.7 MPa push is 879 N, and at 0.9 MPa it is 1130 N. The theoretical maximum force is 128 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40BX250
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40BX250 replacement — usually within 7-8 hours.