This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50X420S, 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 SI50X420S
The AirTAC SI50 Standard Cylinder SI50X420S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 420mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50X420S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke420 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50X420S
- 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 SI50X420S
The AirTAC SI50X420S is a discontinued double-acting ISO 15552 profile cylinder with a 50 mm bore and 420 mm stroke. Delivering 982 N push force at 0.5 MPa through a G1/4 port, it is replaced by the direct replacement SAI50X420S. This upgrade retains identical mounting, stroke, and output force, fitting existing fixtures perfectly.
The SAI replacement features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and long life. The family adds SAIL lock, SAIF valve, and BSAI clamp variants the SI lacked. Your -S magnet works with legacy CS1-B/DS1-B sensors.
Airtac SI50 Standard Cylinder SI50X420S Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50X420S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50X420S |
| Bore size | Ø50 mm |
| Stroke | 420 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 SAI50X420S 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 SAI50X420S 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 SI50X420S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×420 | 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 SI50X420S Is Used
Long-Stroke Diversion
Pushes packages across a 420 mm transfer gap with 982 N of force at 0.5 MPa, using external guides to prevent rod bending.
Component Ejection
Cycles at 30-800 mm/s to eject machined parts from a fixture, utilizing the 30 mm adjustable air cushions for smooth end-of-stroke deceleration.
Replacing the Airtac SI50 Standard Cylinder SI50X420S with the SAI50X420S
To replace the SI50X420S, order the SAI50X420S. Confirm the ISO 15552 mounting accessory (LB, FA, TC, etc.), the G1/4 port, and the -S magnet. The 420 mm stroke is within the 1200 mm standard max, but at this length you must prevent side-load and rod-bending by using external guides. Sizing both ways: a 63 mm bore offers 1559 N push at 0.5 MPa, while a 40 mm bore yields 628 N. A plain cylinder drifts on air loss—the cushion only decelerates—so for load holding use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50X420S
- ✓ 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 SI50X420S FAQ
Yes, the SI50X420S is discontinued. The direct replacement is the SAI50X420S. It is dimensionally interchangeable per ISO 15552, retaining the same 50 mm bore, 420 mm stroke, G1/4 port, and mounting interface.
The G1/4 port bore delivers 982 N push and 825 N pull at 0.5 MPa, 1374 N push at 0.7 MPa, 1767 N at 0.9 MPa, and a theoretical max of 200 kgf at 1.0 MPa. Operating pressure is 0.15-1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50X420S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50X420S replacement — usually within 7-8 hours.