This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50X312S, 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 SI50X312S
The AirTAC SI50 Standard Cylinder SI50X312S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 312mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50X312S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke312 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50X312S
- 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 SI50X312S
The AirTAC SI50X312S is a discontinued double-acting ISO 15552 profile cylinder with a 50mm bore and 312mm stroke. Delivering 982 N push force at 0.5 MPa through a G1/4 port, it is replaced by the SAI50X312S. This direct successor matches the exact ISO 15552 mounting interface, bore, stroke, force, and port size, fitting existing fixtures perfectly.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. For holding loads without live air, the SAI family adds SAIL and BSAI lock variants the SI lacked. The built-in magnet supports CS1-B/DS1-B switches.
Airtac SI50 Standard Cylinder SI50X312S Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50X312S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50X312S |
| Bore size | Ø50 mm |
| Stroke | 312 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 SAI50X312S 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 SAI50X312S 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 SI50X312S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×312 | 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 SI50X312S Is Used
Fixture Clamping
Secures workpieces in machining fixtures, providing 825 N pull force at 0.5 MPa while the G1/4 port maintains adequate flow.
Replacing the Airtac SI50 Standard Cylinder SI50X312S with the SAI50X312S
To replace the SI50X312S, order the SAI50X312S. Verify the ISO 15552 mounting interface, 50mm bore, 312mm stroke, G1/4 port (PT/G/NPT), and mounting accessory. The -S magnet enables CS1-B/DS1-B sensors; the SAI uses current AirTAC switches. Sizing both ways: a 63mm bore yields 1559 N push at 0.5 MPa, while a 40mm bore yields 628 N. Note that 312mm strokes require external guides to prevent rod bending under side loads. A plain cylinder drifts on air loss; for load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50X312S
- ✓ 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 SI50X312S FAQ
Yes, the SI50X312S is discontinued. The direct replacement is the AirTAC SAI50X312S. It shares the identical ISO 15552 mounting interface, 50mm bore, 312mm stroke, output force, and G1/4 port, fitting directly into existing setups.
The 50mm bore features a G1/4 air port and M16x1.5 rod thread. It delivers 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 SAI50X312S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50X312S replacement — usually within 7-8 hours.