This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50X550S, 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 SI50X550S
The AirTAC Airtac SI50 Standard Cylinder SI50X550S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 550mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50X550S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke550 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50X550S
- 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 SI50X550S
The AirTAC SI50X550S is a discontinued double-acting ISO 15552 profile cylinder with a 50mm bore and 550mm stroke. It delivers 982N push force at 0.5MPa via a G1/4 port. AirTAC replaced this legacy unit with the SAI50X550S, a direct upgrade sharing the exact ISO 15552 mounting interface, stroke, and force.
The SAI upgrade features a new piston seal with two Y-shaped one-way elements for low start-up pressure and long life. The original -S magnet supports CS1-B/DS1-B sensors, while the SAI family adds SAIL lock and BSAI clamp-lock variants the SI lacked.
Airtac SI50 Standard Cylinder SI50X550S Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50X550S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50X550S |
| Bore size | Ø50 mm |
| Stroke | 550 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 SAI50X550S 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 SAI50X550S 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 SI50X550S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×550 | 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 SI50X550S Is Used
Material Diversion
Drives long-stroke sorting flaps on packaging lines, utilizing the 982N push force to reliably pivot heavy cardboard cartons at high cycle rates.
Long-Reach Ejection
Pushes molded parts out of large press machinery, requiring the full 550mm extension and adjustable end cushions to decelerate the 20mm rod smoothly.
Replacing the Airtac SI50 Standard Cylinder SI50X550S with the SAI50X550S
To replace the SI50X550S, order the SAI50X550S to retain the exact ISO 15552 interface, 50mm bore, 550mm stroke, G1/4 port, and M16x1.5 rod thread. Confirm your mounting accessory (LB, FA, TC, etc.) and that the -S magnet is specified for current AirTAC switches. Sizing both ways: the neighboring 63mm bore yields 1559N push at 0.5MPa, while dropping to 40mm gives 628N. Because this is a 550mm stroke, use an external guide to prevent rod bending and side-load damage. A plain cylinder drifts on air loss—the cushion only decelerates—so for load holding consider the SAIL lock variant or an external pilot check valve.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50X550S
- ✓ 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 SI50X550S FAQ
Yes, the SI50X550S is discontinued. The direct replacement is the AirTAC SAI50X550S. It is dimensionally interchangeable per ISO 15552, matching the 50mm bore, 550mm stroke, G1/4 port, and mounting interface, but features an upgraded piston seal for longer life.
The G1/4 port is fixed by the 50mm bore. At 0.5 MPa it provides 982N push and 825N pull force. Push force rises to 1374N at 0.7 MPa and 1767N at 0.9 MPa. The theoretical maximum is 200 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50X550S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50X550S replacement — usually within 7-8 hours.