This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50X135SFA, 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 SI50X135SFA
The AirTAC Airtac SI50 Standard Cylinder SI50X135SFA is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 135mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50X135SFA, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke135 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50X135SFA
- 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 SI50X135SFA
The AirTAC SI50X135SFA is a discontinued double-acting ISO 15552 profile cylinder with a 50mm bore and 135mm stroke. It delivers 982N push force at 0.5MPa through a G1/4 port. AirTAC replaced this legacy unit with the SAI50X135SFA, a direct upgrade retaining the exact ISO 15552 mounting interface, stroke, force, and FA flange accessory.
The SAI replacement features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and long life. The SI-SKU includes a magnet for CS1-B/DS1-B sensors, while the SAI family adds SAIL, SAIF, and BSAI lock variants the SI lacked.
Airtac SI50 Standard Cylinder SI50X135SFA Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50X135SFA |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50X135SFA |
| Bore size | Ø50 mm |
| Stroke | 135 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 SAI50X135SFA 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 SAI50X135SFA 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 SI50X135SFA
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×135 | 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 SI50X135SFA Is Used
Clamp Actuation
Provides 982N of clamping force at 0.5MPa for securing mid-weight workpieces during machining operations.
Package Diversion
Drives 135mm stroke diverting arms on packaging lines, moving cartons efficiently at 30-800mm/s.
Replacing the Airtac SI50 Standard Cylinder SI50X135SFA with the SAI50X135SFA
To replace the SI50X135SFA, order the SAI50X135SFA. Confirm the ISO 15552 FA flange mounting, 135mm stroke, G1/4 port, and the -S magnet for current AirTAC switches. For sizing, this 50mm bore yields 982N push at 0.5MPa; if undersized, the 63mm bore provides 1559N. If oversized, the 40mm bore gives 628N. A plain cylinder drifts on air loss as the cushion only decelerates; for load holding, use an external pilot check valve or the SAIL/BSAI lock variant. Stroke is under 300mm so rod bending is minimal, but guide side loads appropriately.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50X135SFA
- ✓ 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 SI50X135SFA FAQ
Yes, the SI50X135SFA is discontinued. The direct replacement is the SAI50X135SFA. It shares the identical ISO 15552 mounting interface, 50mm bore, 135mm stroke, G1/4 port, and FA flange, fitting existing fixtures perfectly.
The 50mm bore uses a G1/4 air port. Force ratings are 982N push and 825N pull at 0.5MPa, 1374N push at 0.7MPa, and a theoretical maximum of 200kgf at 1.0MPa. The piston rod is 20mm with an M16x1.5 thread.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50X135SFA
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50X135SFA replacement — usually within 7-8 hours.