This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50BX25S, 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 SI50BX25S
The AirTAC Airtac SI50 Standard Cylinder SI50BX25S 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 SAI50BX25S, 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 → SAI50BX25S
- 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 SI50BX25S
The AirTAC SI50BX25S is a discontinued double-acting ISO 15552 profile cylinder with a 50 mm bore, 25 mm stroke, and a SUS304 stainless piston rod. Delivering 982 N push force at 0.5 MPa through a G1/4 port, it is replaced by the SAI50BX25S. This direct upgrade shares the exact ISO 15552 mounting interface, stroke, and force.
The SAI upgrade features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and long life. The built-in magnet supports legacy CS1-B/DS1-B sensors, and a Viton H seal option extends heat resistance to 150 C.
Airtac SI50 Standard Cylinder SI50BX25S Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50BX25S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50BX25S |
| 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 SAI50BX25S 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 SAI50BX25S 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 SI50BX25S
| 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 SI50BX25S Is Used
Short-Stroke Clamping
Ideal for holding stainless steel workpieces in machining fixtures where the 25 mm stroke and 982 N force provide firm, precise clamping without overtravel.
Diverting Arm
Acts as a rapid diverting gate on packaging lines, using the 30-800 mm/s speed range to push products off the main belt within a compact 25 mm motion.
Compact Ejector
Suits ejecting small finished goods from press beds, leveraging the SUS304 rod for splash resistance and the 50 kg vertical lift capacity for reliable ejection.
Replacing the Airtac SI50 Standard Cylinder SI50BX25S with the SAI50BX25S
To replace the SI50BX25S, order the SAI50BX25S. Verify the ISO 15552 mounting interface, G1/4 port, M16x1.5 rod thread, and the -S magnet for CS1-B/DS1-B switches. If you need more force, the neighbouring 63 mm bore provides 1559 N push at 0.5 MPa; if less is required, the 40 mm bore offers 628 N. A plain cylinder drifts on air loss—the cushion only decelerates—so use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant to hold loads. The SUS304 rod offers corrosion resistance versus standard carbon steel.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50BX25S
- ✓ 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 SI50BX25S FAQ
Yes, the SI50BX25S is discontinued. The direct replacement is the SAI50BX25S. It matches the ISO 15552 mounting interface, 50 mm bore, 25 mm stroke, 982 N force, and G1/4 port, fitting existing fixtures perfectly.
The G1/4 port feeds a 50 mm bore that generates 982 N push and 825 N pull at 0.5 MPa, 1374 N push at 0.7 MPa, and a theoretical max of 200 kgf at 1.0 MPa. The cushion only decelerates; it does not hold the load on air loss.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50BX25S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50BX25S replacement — usually within 7-8 hours.