This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50BX400S, 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 SI50 Standard Cylinder SI50BX400S
The AirTAC SI50 Standard Cylinder SI50BX400S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 400mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50BX400S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke400 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50BX400S
- 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 SI50 Standard Cylinder SI50BX400S
The AirTAC SI50BX400S is a discontinued double-acting ISO 15552 profile cylinder with a 50mm bore and 400mm stroke. It features a SUS304 stainless piston rod (-B) and a built-in magnet (-S) for CS1-B/DS1-B switches. Delivering 982 N push force at 0.5 MPa, the direct replacement is the SAI50BX400S, matching the G1/4 port, M16x1.5 thread, and 30 mm cushions.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. Note that plain cylinders drift without live air; for held loads, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variants the SI lacked.
Airtac SI50 Standard Cylinder SI50BX400S Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50BX400S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50BX400S |
| Bore size | Ø50 mm |
| Stroke | 400 mm |
| Acting type | Double acting |
| Port size | G1/4 |
| Rod thread | M16×1.5 |
| 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, 30 mm |
| Max standard stroke | Up to 1200 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI50BX400S carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø50mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 982 N | 825 N |
| 0.7 MPa | 1374 N | — |
| Max (@1.0 MPa) | 200 kgf | |
The SAI50BX400S produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI50 Standard Cylinder SI50BX400S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×400 | 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 SI50 Standard Cylinder SI50BX400S Is Used
Long-Stroke Diversion
Pushes heavy packages across a 400mm transfer zone using the 982 N thrust at 0.5 MPa, requiring external guides to absorb side loads.
Pallet Stop Gate
Acts as a 400mm stroke stop gate on roller conveyors, relying on the 30 mm adjustable air cushions to decelerate moving pallets smoothly.
Replacing the Airtac SI50 Standard Cylinder SI50BX400S with the SAI50BX400S
To replace the SI50BX400S, order the SAI50BX400S. Confirm the ISO 15552 mounting interface, 50mm bore, 400mm stroke, G1/4 port (PT/G/NPT), and mounting accessory. The -B SUS304 rod and -S magnet (using current AirTAC switches) carry over. At 0.5 MPa it yields 982 N push; neighbouring bores offer 628 N (40mm) or 1559 N (63mm). Because 400mm exceeds 300mm, add external guides to prevent rod bending and side-load wear. The cushion only decelerates; it does not hold load on air loss, so specify a pilot check valve or SAIL lock if needed.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50BX400S
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI50 Standard Cylinder SI50BX400S FAQ
Yes, the SI50BX400S is discontinued. The direct replacement is the SAI50BX400S. It is dimensionally interchangeable per ISO 15552, retaining the same 50mm bore, 400mm stroke, 982 N force, G1/4 port, and mounting interface.
The 50mm bore features a G1/4 air port and M16x1.5 rod thread. Forces are: 982 N push and 825 N pull at 0.5 MPa, 1374 N push at 0.7 MPa, 1767 N push at 0.9 MPa, and a theoretical max of 200 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50BX400S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50BX400S replacement — usually within 7-8 hours.