This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125BX550, 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 SI125 Standard Cylinder SI125BX550
The AirTAC SI125 Standard Cylinder SI125BX550 is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 550mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125BX550, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke550 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125BX550
- 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 SI125 Standard Cylinder SI125BX550
The AirTAC SI125BX550 is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 550 mm stroke. Delivering 6136 N push force at 0.5 MPa, it features a SUS304 stainless piston rod (B option) for corrosion resistance. The direct replacement is the SAI125BX550, retaining the exact G1/2 port, M27x2 thread, and mounting interface.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and extended life. Note this SKU lacks a magnet and cannot accept a sensor; the legacy SI used CS1-B/DS1-B switches. For high-heat environments, a Viton H seal option raises the operating ceiling to 150 C.
Airtac SI125 Standard Cylinder SI125BX550 Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125BX550 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125BX550 |
| Bore size | Ø125 mm |
| Stroke | 550 mm |
| Acting type | Double acting |
| Port size | G1/2 |
| Rod thread | M27×2.0 |
| 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 – 500 mm/s |
| Cushion | Adjustable, 40 mm |
| Max standard stroke | Up to 1500 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI125BX550 carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø125mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 6136 N | 5734 N |
| 0.7 MPa | 8590 N | — |
| Max (@1.0 MPa) | 1251 kgf | |
The SAI125BX550 produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI125 Standard Cylinder SI125BX550
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×550 | 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 SI125 Standard Cylinder SI125BX550 Is Used
Heavy Stamping Press
Drives large platens and tooling in metal forming, utilizing the 6136 N push force to shape thick gauge materials reliably.
Pallet Transfer Unit
Indexes heavy loaded pallets over the 550 mm travel distance, requiring external guide rails to prevent rod deflection.
Rubber Mold Clamping
Secures industrial molds at elevated temperatures using the SUS304 rod option, with Viton H seals for thermal stability.
Replacing the Airtac SI125 Standard Cylinder SI125BX550 with the SAI125BX550
To replace the SI125BX550, order the SAI125BX550. Verify your ISO 15552 mounting interface (LB, FA, TC, etc.), the 550 mm stroke, and the G1/2 port. Because this is a non-magnet SKU, it cannot support position sensing; if switches are needed, select an SAI equivalent with the S suffix. For sizing alternatives, dropping to a 100 mm bore yields 3927 N push at 0.5 MPa, while a 160 mm bore provides 10053 N. With a 550 mm stroke, external guides are strongly recommended to prevent rod bending and manage side loads. A plain cylinder will not hold a load without air; use an external rod lock, pilot check valve, or the SAIL/BSAI lock variants for secure holding.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125BX550
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI125 Standard Cylinder SI125BX550 FAQ
Yes, the AirTAC SI125BX550 is discontinued. The direct replacement is the SAI125BX550. It is dimensionally interchangeable per ISO 15552, offering the same 125 mm bore, 550 mm stroke, 6136 N force, G1/2 port, and mounting interface.
At 0.5 MPa it provides 6136 N push and 5734 N pull force. At 0.7 MPa push is 8590 N, and at 0.9 MPa it is 11045 N. The theoretical max force is 1251 kgf at 1.0 MPa. Operating speed for this 125 mm bore is 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125BX550
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125BX550 replacement — usually within 7-8 hours.