This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50BX185, 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 SI50BX185
The AirTAC SI50 Standard Cylinder SI50BX185 is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 185mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50BX185, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke185 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50BX185
- 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 SI50BX185
The AirTAC SI50BX185 is a discontinued double-acting ISO 15552 profile cylinder with a 50mm bore, 185mm stroke, and G1/4 port. It delivers 982N push and 825N pull at 0.5MPa. The direct replacement is the SAI50BX185, sharing the exact ISO 15552 mounting interface, bore, stroke, force, and port. This SKU features a SUS304 stainless piston rod (-B) for corrosion resistance, but lacks a magnet (-S) so it cannot accept a magnetic switch. The SAI upgrade uses two Y-shaped piston seals for low start-up pressure and long life.
Because 185mm is a non-standard stroke, the SAI50BX185 will be built to this exact length. The original SI family lacked integrated lock options, but you can now specify the SAIL (air-released lock) or BSAI (clamp-lock) variants for secure holding. The standard cushion is 30mm at each end, and the -B rod material prevents rust in washdown environments.
Airtac SI50 Standard Cylinder SI50BX185 Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50BX185 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50BX185 |
| Bore size | Ø50 mm |
| Stroke | 185 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 SAI50BX185 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 SAI50BX185 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 SI50BX185
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×185 | 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 SI50BX185 Is Used
Stainless Rod Clamping
Uses the SUS304 rod (-B) for corrosion resistance when clamping parts in humid or lightly washdown machining cells.
Mid-Force Diverting
Provides 982N push at 0.5MPa to divert packages on a conveyor line, with a 30mm cushion absorbing end-of-stroke impact.
Replacing the Airtac SI50 Standard Cylinder SI50BX185 with the SAI50BX185
To replace the SI50BX185, order the SAI50BX185. Confirm the ISO 15552 mounting interface (LB, FA, FB, CA, CB, TC), the 50mm bore, the 185mm stroke, and the G1/4 port. This non-standard 185mm stroke is supported but requires custom assembly. Since this SKU has no magnet (-S), it cannot take a sensor; if you need position feedback, order the SAI equivalent with the S suffix and use current AirTAC switches (legacy SI used CS1-B/DS1-B). Sizing both ways: the 50mm bore gives 982N push at 0.5MPa; if you need less force, the 40mm bore offers 628N, and if you need more, the 63mm bore offers 1559N. For load holding, a plain cylinder drifts on air loss—the cushion only decelerates. Use an external pilot check valve, a rod lock, or the SAIL/BSAI lock variant. For any stroke over 300mm, add a guide to prevent rod bending.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50BX185
- ✓ 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 SI50BX185 FAQ
Yes, the SI50BX185 is discontinued. The direct replacement is the SAI50BX185. It is dimensionally interchangeable per ISO 15552, matching the 50mm bore, 185mm stroke, G1/4 port, and mounting interface.
The G1/4 port feeds the 50mm bore, delivering 982N push and 825N pull at 0.5MPa, 1374N push at 0.7MPa, and a theoretical max of 200kgf at 1.0MPa. The rod is Ø20mm with an M16x1.5 thread.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50BX185
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50BX185 replacement — usually within 7-8 hours.