This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50X25STC, 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 SI50X25STC
The AirTAC Airtac SI50 Standard Cylinder SI50X25STC is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 25mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50X25STC, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke25 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50X25STC
- 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 SI50X25STC
The AirTAC SI50X25STC is a discontinued double-acting ISO 15552 profile cylinder with a 50 mm bore and 25 mm stroke. It delivers 982 N push force at 0.5 MPa through a G1/4 port. The direct replacement is the SAI50X25STC, matching the exact ISO 15552 mounting interface, TC trunnion, and output force.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure and long life. The SAI family also adds SAIL, SAIF, and BSAI lock variants the SI lacked. Your -S magnet works with legacy CS1-B/DS1-B sensors.
Airtac SI50 Standard Cylinder SI50X25STC Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50X25STC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50X25STC |
| Bore size | Ø50 mm |
| Stroke | 25 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 SAI50X25STC 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 SAI50X25STC 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 SI50X25STC
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×25 | 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 SI50X25STC Is Used
Short-Stroke Clamping
Ideal for holding parts in machining fixtures where a compact 25 mm stroke provides rapid 982 N clamping action.
Package Diverting
Snappy 25 mm extension pushes cartons off a conveyor belt, utilizing the 30-800 mm/s speed range for high throughput.
Gate Ejection
Mounts via TC trunnion to pivot an ejection gate, delivering precise 825 N pull force to clear finished components.
Replacing the Airtac SI50 Standard Cylinder SI50X25STC with the SAI50X25STC
To replace the SI50X25STC, order the SAI50X25STC. Verify the ISO 15552 TC trunnion mount, 50 mm bore, 25 mm stroke, G1/4 port, and the -S magnet for CS1-B/DS1-B switches. For sizing, the 40 mm bore yields 628 N push at 0.5 MPa, while the 63 mm bore provides 1559 N. A plain cylinder drifts without live air; the cushion only decelerates. For load holding, use an external pilot check valve or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50X25STC
- ✓ 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 SI50X25STC FAQ
Yes, the SI50X25STC is discontinued. The direct replacement is the SAI50X25STC. It is dimensionally interchangeable per ISO 15552, retaining the same 50 mm bore, 25 mm stroke, G1/4 port, TC mount, and force ratings.
The G1/4 port feeds a 50 mm bore yielding 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 200 kgf maximum at 1.0 MPa. The SAI upgrade adds a two Y-shaped one-way piston seal for low start-up pressure.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50X25STC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50X25STC replacement — usually within 7-8 hours.